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Report April 21, 2022

Climbing the ladder: How the West can manage escalation in Ukraine and beyond

By Richard D. Hooker, Jr.

Table of contents


Moscow’s invasion of Ukraine is transforming Europe’s security architecture, as well as NATO’s strategic priorities and its defense and deterrence posture. Russia’s ruthless aggression and NATO’s response increase the possibility of purposeful or inadvertent escalation in Europe. Whether this takes the form of heightened conflict in Ukraine, increased tension across the whole or parts of NATO’s eastern flank—from Ukraine and the Black Sea to the Baltic Region and the High North—or in non-kinetic, subthreshold domains, understanding how these dynamics might degrade transatlantic stability is critical. This study will seek to identify key rungs on the escalation ladder around the war in Ukraine; assess how the current crisis might escalate inside Ukraine and across NATO’s eastern flank; explore how the US and NATO posture can prevent or limit escalation; and offer recommendations for how the United States and NATO can adapt their strategy, posture, and activities to manage escalatory dynamics.

In response to the invasion of Ukraine, the West has imposed stinging sanctions, disrupting the Russian economy and forcing the Kremlin to burn through its financial reserves. Major Russian banks have been disconnected from SWIFT, the international system that facilitates financial transactions, while some oligarchs have been sanctioned. Many allies and partners have provided massive financial and material aid—in the form of funding, as well as anti-tank and air-defense systems and other military equipment—to bolster Ukrainian resistance. This assistance has helped to stiffen an already stout Ukrainian defense, which has inflicted heavy losses on the Russian military. Vladimir Putin now faces the real possibility of a stalled offensive, or even outright defeat.

In this circumstance, Russia still has cards to play. Failure in Ukraine places Putin’s political survival at risk and he is, therefore, unlikely to withdraw. His present difficulties are more likely to provoke escalation within or around Ukraine, both in the military realm and in other domains. As he climbs the escalation ladder, Putin’s risk tolerance will increase, as his key subordinates will surely realize. The ultimate risks, however, are removal from office, imprisonment, or even execution. Accordingly, Putin is far more likely to press harder in Ukraine than to acquiesce to a negotiated settlement that leaves him without tangible gains.

The following discussion of Russian escalatory options is linked to the progress of the campaign in Ukraine and presents alternate scenarios based on Russian progress or failure and the degree to which the West provides critical support and/or direct intervention. Escalatory steps are described in ascending order of severity and risk. Response options to control or mitigate Russian escalation follow. It is important to note that Russian, Ukrainian, and Western perspectives or “lenses” on what is escalatory may differ significantly in both time and space. This factor must be borne in mind when assessing adversary actions.  

Escalation triggers

As Putin and his senior advisers consider options, conditions on the ground will drive their calculus. Should the Russian military manage to recover its footing and resume progress, however halting, more extreme options may be held in reserve. If the campaign evolves into a “frozen” conflict, like the Donbas but on a larger scale, Putin’s focus will shift to destabilizing the Volodymyr Zelenskyy regime in Kyiv and sanctions relief. Should Ukraine achieve decisive success in recovering its national territory, Putin’s survival may be at risk, and incentives to employ harsher and more high-risk measures will grow. Escalation to each of the below “rungs” will depend on Putin’s perception and assessment of how the campaign is progressing and the prospects for ultimate success or failure. Though speculative, likely triggers for escalation into each subsequent phase of the conflict might include

  • an assessment that the campaign has stalled temporarily and different approaches are needed to regain momentum;
  • an assessment that the campaign has stalled outright and recovery is unlikely without more extreme measures; and
  • an assessment that defeat is imminent, and that Putin may fall from power, placing all his options on the table.

As the conflict drags on, NATO and European Union (EU) actions can be decisive one way or the other, as described further below.

“We are already seeing the first round of escalation as Putin comprehends the failure of his initial invasion.”

A view shows a residential building destroyed in the course of Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 14, 2022. Picture taken with a drone. REUTERS/Pavel Klimov

The first rung

We are already seeing the first round of escalation as Putin comprehends the failure of his initial invasion. Russian forces have partially or completely encircled key Ukrainian cities like Kharkiv, Mariupol, and others. In the absence of decisive military success on the ground, they have resorted to indiscriminate attacks and atrocities in civilian areas to cause terror and break Ukraine’s will to resist. These measures suggest an indifference to international public opinion that may become even more pronounced in the weeks and months to come. In the near term, further loss of power, food, medicine, and fuel will impose cruel hardships on the civilian population. Attacks on the Zaporizhzhia nuclear plant, the siege of Mariupol (which has killed thousands of civilians), and attacks on cultural sites like the Babi Yar Holocaust Memorial in Kyiv make clear that the gloves have come off.

As evacuation of civilians becomes more difficult or ceases, the pressure on President Zelenskyy to capitulate or agree to harsh terms (such as the surrender of Ukrainian territory, a pledge not to join NATO or the EU, and the presence of Russian troops in Ukraine (as in Armenia, Azerbaijan, Georgia, and Moldova)) will intensify. Russia has also begun to launch attacks in western Ukraine near the Polish border, signaling that further attempts to supply Ukraine with lethal aid will be opposed. Threats to raise nuclear alert levels; the movement of mobile intercontinental ballistic missiles (ICBMs) through the streets of Moscow; the recruitment of Syrian soldiers and foreign mercenaries; and the apparent “stop loss” of conscripted soldiers approaching the end of their contract periods also represent expansion or escalation of the conflict.

Major powers like China, India, and Brazil have so far failed to condemn Russia, but are not likely to provide military support. The Russian Federation has not employed major cyberattacks, halted energy deliveries or agricultural exports, jailed foreign nationals in large numbers, or defaulted on loans owed to foreign banks. These and many other escalatory options may be encountered as events unfold and Putin becomes more desperate.

The second rung

The latest phase of the conflict will be decided in the coming weeks. Should Kharkiv and Mariupol ultimately fall in Russia’s new offensive in the Donbas and surrounding areas, other Russian advances in eastern and southern Ukraine could roll up the Ukrainian defense—potentially all the way to the Dnepr in the most devastating scenarios—effectively ceding the eastern half of the country to Russian control. A major part of Ukraine’s regular forces will be lost, and the narrative will shift as Russian offensive gains replace the dominant storyline of an obstinate Ukrainian defense. Given heavy losses, international condemnation, and crushing sanctions, this may be enough to drive a negotiated settlement: a cessation of Russian attacks in exchange for promises of neutrality and Russian de facto, if not de jure, control of eastern Ukraine. Putin might well claim victory, reconsolidate, work to undermine Zelenskyy’s government, and hope to install a pro-Moscow regime as before.

Surging forces and increasing destructive activity. At present, however, Ukrainian collapse does not look probable. Should Ukrainian defenses hold in the east, or if Zelenskyy continues to defy Moscow and continue the fight without concessions, Putin will face more difficult choices. Internal dissent will continue to rise as casualties mount and economic hardships and diplomatic isolation intensify. Putin has already committed most of his available conventional forces to the conflict, and Russian stocks of precision-guided munitions, including ballistic missiles, have been drawn down. His next steps will be to expand conscription, mobilize reserves, strip outlying areas of their garrisons, and increase pressure on commanders to achieve results by threatening relief, imprisonment, or even execution. Any remaining restraints on attacks on civilians will be relaxed, as seen in Grozny and Aleppo. Artillery, air, and missile strikes against cities will intensify, and targeted arrests and assassinations of Ukrainian officials will become more frequent. Nuclear plants in occupied areas may also be shut down to kill power in urban areas.

As it did in the Chechen wars, the Russian military will learn from its failures and adapt its tactics. To date, the integration of airpower, artillery fires, and electronic warfare with maneuver forces has been unimpressive. This will likely improve, though perhaps not dramatically. Damaged forces will be pulled back to be reconstituted and reequipped, though replacements are likely to be poorly trained. A chaotic command and control structure, with a theater commander to coordinate the twelve army and two corps headquarters in Ukraine, is under revision. Although a theater commander has been appointed, we do not know if he commands all army formations, or if his authority extends to special-operations forces, airborne forces, naval infantry, the national guard, and other various formations of the Russian Armed Forces and security services. The use of “battalion tactical groups” with their own artillery has clearly failed. Reversion to the more traditional regiments, brigades, and divisions may follow, along with a recentralization of field artillery to generate more powerful effects.

“As Western-provided lethal aid becomes more and more decisive, Putin will step up his efforts to interdict ground lines of communication, raising the chances of fires that stray across national boundaries into NATO territory.”

Ukrainian service members unpack Javelin anti-tank missiles, delivered by plane as part of the U.S. military support package for Ukraine, at the Boryspil International Airport outside Kyiv, Ukraine February 10, 2022. REUTERS/Valentyn Ogirenko

We can expect more nuclear threats, backed up by the visible deployment of tactical nuclear systems in the theater of operations. Use of primitive weapons of mass destruction (WMD), such as chlorine gas, may well begin to increase terror. As Western-provided lethal aid becomes more and more decisive, Putin will step up his efforts to interdict ground lines of communication, raising the chances of fires that stray across national boundaries into NATO territory. While probably intentional, these may be dismissed as accidental or Western provocations.

Due to naval limitations imposed by the Montreux Convention, Russian maritime forces are dominant in the Black Sea and provide options for signaling, as well as combat operations. To show resolve and seriousness of intent, Russian commanders there may begin to stop or board commercial vessels at sea, bombard coastal cities, violate territorial waters, interdict coastal motorways and rail lines, and land troops in key locations. Major amphibious operations—for example, to take Odesa—are not likely without cooperation from land forces.

Expanding use of nonmilitary measures. In the information domain, Russia in this stage is likely to persist in spreading false stories about Ukrainian and NATO nuclear, biological, and chemical threats and their intent to “dismember” Russia. These will have little impact outside Russia but, given Putin’s control of state media, will contribute to domestic support for the conflict. Damaging cyberattacks may be delivered against targets in Poland, the Baltic States, and perhaps other states providing lethal aid, though catastrophic denial of service, attacks on the financial sector or electrical grid, or ransomware attacks against the United States may be held in reserve. Propaganda and disinformation directed against President Zelenskyy and his government will continue and intensify, as will attempts to decapitate Ukrainian leadership and regional and local officials through targeted assassinations.

On the economic front, Putin retains flexibility through a range of remaining options, though each could either help or hinder his efforts. The most powerful is to stop the sale of oil and natural gas to Central and Eastern Europe (some nations are almost completely dependent on Russian energy). Most European allies and partners do not possess strategic reserves or the necessary infrastructure (e.g., pipelines or terminals and storage tanks for liquified natural gas) to rapidly transition to alternate sources. This step will surely influence European parliaments and societies, and also deprive Russia of badly needed currency reserves.

Though energy is by far Russia’s most important export commodity, cutting off shipments to Europe would drive up prices globally, place severe pressure on European governments, and drive wedges between those states that are dependent on Russian energy and others that are less so. In this phase of the campaign, Putin will likely threaten to cut deliveries or implement minor disruptions to warn targeted nations that continued assistance to Ukraine could result in harsher steps.

Putin is also taking initial steps to nationalize assets held by EU and US companies in Russia. To date, almost four hundred foreign companies have moved to divest or wind down their businesses in Russia, creating severe pressure on the Russian economy. Nationalizing those companies’ assets will affect profitability, and may give Putin a temporary public-relations boost domestically. But, in the long term, Russia in most cases will probably not be able to take over and run these operations successfully.

The Russian government may also elect to default on the $56 billion owed to European banks, as its access to funds deposited abroad are sequestered and its cash reserves are consumed by crippling sanctions. This default can be caused by Russia’s inability to service its foreign debt, or could be a conscious decision by Russian finance officials. While this option carries long-term consequences, such as loss of access to foreign capital and diminished investor confidence, the global economy will not be shaken as it was by the 1998 Russian default. Many foreign investors reduced their exposure following the 2014 sanctions. Though painful, a Russian default now will not be as potent.

Although Russian energy dominates its export market, Russia’s agricultural and mineral products are also critical to global prosperity. Russia accounts for 13 percent of the world’s total fertilizer production, while Russia and Ukraine together supply more than 25 percent of the world’s total wheat crop. The fighting in Ukraine has seen Russian forces deliberately target food-storage sites and will affect the spring planting, as many agricultural workers have joined the territorial defense forces. But, Russia may also withhold wheat and fertilizer exports, leading to much higher prices and a potential global food crisis. This has already begun. Russia is also one of the world’s biggest suppliers of nickel. The invasion of Ukraine created so much uncertainty about supply chains for nickel that the market soon soared “out of control,” generating billions of dollars in losses. Russia is also the world’s largest exporter of palladium, a critical material in the manufacture of catalytic converters. Following the invasion of Ukraine and imposition of flight restrictions on Russian carriers, palladium prices reached all-time highs in March 2022. As with energy, manipulation of these commodities can serve as an escalatory option to real effect if employed strategically.

The third rung

Should the campaign in Ukraine continue through the spring and into the summer without a decisive result, pressure on Putin and the Russian state will intensify. As sanctions bite, Russian casualties mount, and international support for Ukraine increases, the prospects for a decisive outcome in Russia’s favor will wither. Avoiding defeat and the security of the regime will become overriding priorities. Absent a diplomatic solution that can be sold as a Russian victory worth the sacrifice, Putin will persevere and act even more harshly.

Devastating cities to a higher degree. On the military front, if major Ukrainian urban areas continue to hold out, the range of available options for Russian forces will begin to shrink. Taking these cities intact by direct assault is unlikely, given the extraordinary losses already sustained, the low quality demonstrated by Russian conventional forces, and high Ukrainian morale. As lethal aid for Ukraine continues to flow, the Russian military will likely fall back on its remaining strengths. Chief among them is a prodigious amount of rocket and tubed artillery, and a vast inventory of Cold War-era munitions. More widespread use of thermobaric terror weapons like the 220-milimeter TOS-1 and TOS-2 systems, as well as white-phosphorous and napalm weapons, can be expected. With these, Russian forces can do more than attack cities; they can level them.

Direct-fire systems can be used in this mode as well. After initial failures in Grozny, Russian forces resorted to brute force, using tanks to demolish buildings with high-explosive rounds fired in great numbers from long range. Field artillery was also used in the direct-fire mode in Chechnya, with devastating results. In this way, lightly armed defenders with handheld anti-tank weapons were destroyed before they could attack Russian tanks. While fighting in cities poses many risks for Russian armor, one advantage is the greater difficulty faced by defenders in employing the top-attack Javelin in urban terrain. Once targeted urban areas have been reduced by devastating long-range fires, opportunities to engage and defeat the stunned and demoralized defenders improve. Demolishing large urban centers to destroy resistance will also affect the will to resist across Ukraine as a whole.

Redoubling efforts to achieve success in open-field combat. As summer approaches and off-road trafficability improves—and after a period of regrouping, retraining, and reorganization—Russian forces will redouble their efforts to encircle the mass of Ukrainian armor and artillery fighting in eastern Ukraine from north and south, an effort already under way. These represent a large part of the Ukrainian “first echelon” order of battle. President Zelenskyy has risked much by exposing these valuable forces to encirclement, but so far the risk has paid off. If they are cut off and destroyed, the Ukrainian defense in the east will collapse (except for continued resistance by territorial defense forces in the cities and insurgency in the countryside). This kind of success will open the door for diplomatic opportunities, such as an offer of peace and cessation of hostilities in exchange for a guarantee of Ukrainian neutrality and the “demilitarization” of eastern Ukraine. Annexation of Luhansk and Donetsk will almost certainly follow.

Further cutting lines of communications and supply. At the operational level, Russian commanders in this phase will be seized with the importance of cutting ground lines of communication in western Ukraine used to resupply Ukrainian forces and keep the war going. Surprisingly effective Ukrainian air defense has inflicted heavy losses on Russian aircraft, which often launch their weapons from Belarus or Russian airspace. Aerial and missile fires can be employed against fixed sites like storage or transshipment points, but, at present, the Russian army does not have a strong ground presence in western Ukraine. Instead, more highly trained special-operations units may be used to interdict ground convoys. As the campaign unfolds, sustained foreign assistance will mount in importance. As Russian desperation increases, Putin will attempt to signal that continued use of Polish and Romanian territory to supply Ukraine will have drastic consequences. Painful cyberattacks, covert and deniable intelligence operations, and other hybrid methods may be used for this purpose, including in the United States. In this phase, Putin will not order direct attacks on neighboring NATO countries for fear of bringing the Alliance into the war.  

Raising the specter of nuclear attack. As the crisis worsens for Russia, the role of nuclear weapons will loom larger. In this phase of escalation, more strident threats to employ them will be accompanied by the overt display of tactical and strategic systems, publicized “drills,” repositioning of nuclear systems, and other activities intended to frighten and intimidate. Use of primitive chemical agents like chlorine will become more likely if campaign success eludes Russian forces. A demonstration or “test” using a low-yield tactical nuclear weapon in a remote area near the Ukrainian border could occur to add weight to these threats. Russian journalists, academics, and retired military and intelligence officers with contacts in the West will be enlisted to convey a determination to escalate further, if necessary, though such measures will carry extreme risk. 

“Should the campaign in Ukraine continue through the spring and into the summer without a decisive result, pressure on Putin and the Russian state will intensify.”

The Kyiv TV Tower is hit by Russia strike on March 1, 2022 as Russia’s invasion Smoke rises after military strikes, as Russia’s attack on Ukraine continues, in Lviv, Ukraine April 18, 2022. REUTERS/Roman Baluk

Targeting communications infrastructure. So far, Russia has not attempted to shut down Ukrainian cellphone usage, partly to preserve telecommunications infrastructure for later use, but also to listen in on Ukrainian communications and to use the network itself. As the prospect of victory recedes, Putin may reassess and decide to destroy cell towers and other facilities to restrict Ukrainian social media and internal communications. This will disrupt Russian intelligence gathering, but also degrade Ukrainian civil and military communications and limit use of social media. However, given the large number of providers in Ukraine, complete loss of coverage or service is unlikely.

Heightening existential rhetoric. As internal opposition begins to organize and stiffen, Putin must strengthen his case for war and continued military action. He will do so by emphasizing manufactured threats to Russian territory, the Russian people (inside and outside Russia’s borders), and Russian culture. As they have to date, these themes will compete poorly with the reality shown daily around the world in media reporting and social media. Russian disinformation will continue to amplify threats to the Russian homeland and the Russian diaspora to portray the campaign not as a war to “liberate” Ukraine, but as a defense against an existential threat to the survival of the state itself. Putin might enlist the Russian Orthodox Church more prominently than ever before in an effort to portray the conflict in spiritual, as well as nationalist, terms. The reincorporation of Ukraine, in whole or in part, will now take on the character of a crusade.

To date, Russian cyber capabilities have been employed largely in direct support of Russia’s military effort, for instance, against Ukraine’s military, intelligence, and police communications systems. Now, Putin will probably unleash comprehensive, full-spectrum cyberattacks against Ukrainian government, military, financial, and commercial nodes, in addition to sharp, but not full-scale, offensive cyber activity outside Ukraine.

Disrupting oil and gas shipments. At this level of escalation, Putin is likely to remind NATO and the European Union of his economic clout by more painfully halting or disrupting oil and natural-gas shipments. This will drive energy prices even higher, contribute to power outages or rationing, and inflame opposition parties. Other critical exports may also be halted by government decree. The intent here is to generate internal domestic pressure in European capitals to cease or reduce military and economic assistance to Ukraine, and to create pressure for a diplomatic settlement favorable to Russia. These moves will be painful inside Russia and represent a calculated risk—loss of revenue and investor confidence will shock the Russian economy even more harshly—but, at this point, Putin will need game changers to reverse a disastrous and deteriorating situation.              

To stave off defeat, Putin must achieve a diplomatic settlement that leaves him with more than he possessed at the outset. In all likelihood, this means a pledge of Ukrainian neutrality and the total, not partial, occupation of Luhansk and Donetsk, their incorporation into the Russian Federation, and possession of Mariupol and a land bridge to Crimea. Well-meaning leaders in the West will be tempted to agree to these conditions to “stop the killing,” but this outcome can only reward Russian aggression and lead to more of the same in future years.  

The fourth rung

Consolidating gains. Six months into the campaign, Russia will face one of two outcomes. The first is gradual progress through a combination of mounting Ukrainian losses—both military and civilian—that lead to the loss of major urban centers and major groupings of regular forces. Shortages of food, fuel, spare parts, and precision-guided munitions—as well as attrition of major combat systems, such as combat aircraft, main battle tanks, high-altitude air-defense weapons, and self-propelled artillery—could, in time, wear down Ukraine’s defense if not quickly replaced by friendly states. Grinding attrition and catastrophic destruction of industry, agricultural areas, and infrastructure may then force the Ukrainian government to accept a diplomatic settlement that will allow Putin to claim victory. Such a settlement could include Ukrainian acceptance of Russian sovereignty over Crimea, Luhansk, Donetsk, and perhaps Kharkiv and Mariupol, as well as a pledge of permanent neutrality. Putin would also insist on easing of international sanctions as a precondition for a ceasefire. Despite serious losses and tactical defeats, it is too early to count Russia out.

In this case, Putin is likely to consolidate his gains, rebuild and improve his forces, stabilize his internal domestic politics and economy, and attempt to reestablish working relationships with Europe—above all, with Germany. Even costly success in Ukraine will not, however, satisfy Putin. The invasion of Ukraine should be seen as another step in an historic process that includes military aggression in Chechnya, Georgia, Crimea, and the Donbas, as well as the deployment of Russian troops in frozen conflicts in Armenia and Moldova. Further aggression in areas formerly belonging to the Russian empire—above all, the Baltic States—is highly likely following a period of reorganization and recovery. 

Avoiding a stalemate or defeat through extreme escalation. The second outcome is a prolonged stalemate or outright defeat. In this scenario, after staggering losses and a scorched-earth campaign throughout Ukraine, Russian forces remain stalled. Ukrainian regular forces have suffered high losses but remain largely intact with high morale, while territorial defense forces continue to fight effectively. Ukrainian performance is actually improving with combat experience, as well as growing confidence and elan. Western material and financial support remains strong.

Internally, domestic unrest in Russia will become a serious threat to Putin’s regime, as crushing economic hardships mount and Russian losses and lack of military success become more widely known. Russian oligarchs facing financial ruin—as well as government, intelligence, and military elites who fear Putin’s wrath and state collapse—may act to remove Putin from power. Pressure to resolve the conflict and reassert control may become overwhelming.

“In this scenario, Putin will have to consider more extreme and high-risk strategies to stave off defeat, prevent economic collapse, divert public opinion, and stay in power. Even more than success in Ukraine, regime survival will become the overriding priority.”

Russian President Vladimir Putin observes exercise of the strategic deterrence force in Moscow on February 19, 2022. Photo by Aleksey Nikolskyi/Sputnik/Kremlin via REUTERS

Transitioning the conflict in Ukraine into a frozen conflict lasting years, as has been done in the Donbas since 2014, may be Putin’s best option now. A resolute Ukrainian government and highly motivated Ukrainian forces will continue to fight to reassert sovereignty over the national territory. Continued Western support will enable Ukrainian forces to grow stronger, though it may not be possible to retake the areas newly controlled by Russia without more armor and combat aircraft. In this scenario, Putin will have to consider more extreme and high-risk strategies to stave off defeat, prevent economic collapse, divert public opinion, and stay in power. Even more than success in Ukraine, regime survival will become the overriding priority.

With this in mind, what escalatory options could Putin choose?

Employing cyber tools. Under such desperate circumstances, Putin may elect to employ the full scope of his offensive cyber capabilities, which are formidable. Repeatedly in recent years, Russian cyber weapons have been employed successfully. While Russia has employed its cyber tools at the tactical level to some success in Ukraine, for reasons that remain somewhat unclear, the potential strategic effects of these weapons have been held in reserve so far in the campaign. Potential targets could include critical infrastructure such as power and transportation grids, nuclear-power plants, healthcare systems, government operations, the financial sector, and military command and control in the United States and Europe. These attacks would certainly invite retaliation, but Putin may see them as warranted to stave off defeat and preserve his regime.

Employing WMD. Putin may also choose to resort to weapons of mass destruction to cow the Ukrainian public and frighten off Western support. This could take the form of chemical strikes using military-grade chemical agents, such as nerve or mustard gas (although a signatory to the 1993 Chemical Weapons Convention, Russia is known to retain substantial stocks). Russia has already accused Ukraine and the United States of establishing chemical- and biological-weapons facilities inside Ukraine, a likely precursor to its own use. Russian formations field organic nuclear, biological, and chemical (NBC) protection units at all levels, from brigade to combined-arms army, and Russian planners will surely contemplate using them if faced with a humiliating defeat.

Employing nuclear weapons. Use of tactical nuclear weapons inside Ukraine is also a possibility in a last bid to achieve military success, although senior Russian military officials may balk at such an extraordinarily risky step. As NATO’s nuclear umbrella does not extend over Ukraine, Putin may discount the chance of retaliation. An added benefit could be a sharp warning of Russia’s willingness to use nuclear weapons if provoked—for example, if NATO ultimately entered the conflict to save a foundering Ukraine. This option would take the form of low-yield tactical weapons, launched from aircraft or field artillery, or delivered via Iskander-M short-ranged ballistic missiles or Kalibr cruise missiles. Such use would not necessarily lead to uncontrolled escalation, and is well within the calculus of Russian military doctrine. The shock of such an event would be profound, and could lead to Ukraine’s submission or acceptance of unfavorable terms. Similarly, Russian forces could engineer a nuclear “accident” involving one or more of Ukraine’s fifteen reactors, located at Yuzhnukraines, Rivne, Khmelnitsky, and Zaporizhzhia. (Chernobyl, located one hundred kilometers north of Kyiv, is not operational, but still houses large amounts of radioactive material.) The spread of radioactive fallout would, however, be very weather dependent, making this a very high-risk venture. Unquestionably, Russia would be condemned even by its few remaining supporters, to say nothing of an aroused and angry international community. At this stage, Russia is already an international pariah, with little moral currency left to lose. Ordering the use of tactical nuclear weapons could well be game changing. It might also drive Putin from power.

Destabilizing areas outside Ukraine. On the diplomatic and intelligence fronts, other possibilities also exist. The Russian government could further interfere in Transnistria or annex South Ossetia and Abkhazia, further complicating regional stability. Hostage taking—the arrest and detention of diplomats, journalists, business executives, missionaries, and other foreign nationals—would provide real leverage and help to extract concessions. Targeted, non-attributed assassinations in foreign countries are well within Russian capabilities, and could sow confusion and help to destabilize opponents.

Russian information operations, so vaunted before the invasion of Ukraine, will be of limited use now. Russian credibility abroad is so low, and the evidence of Russian atrocities so overwhelming, that false-flag operations, fake news, doctored videos, and tortured narratives will not gain traction outside Russia and, over time, might be more and more discounted inside. Similarly, few economic, financial, or commercial options will exist once exports of critical commodities have been shut off. An unintended consequence will be the development of alternate sources of supply for European and global customers, much as Great Britain and France found other suppliers for cotton during the Civil War once southern shipments were embargoed. Loss of international credit, the collapse of the ruble, exhaustion of financial reserves, and lack of access to capital held outside Russia will see Russia approaching economic collapse.

In short, while these more extreme escalatory options deserve consideration, most would leave Russia in even worse shape and at greater risk. Russian elites almost certainly see this. The more moderate and sensible approach—to withdraw to pre-war boundaries, offer concessions to Ukraine and the West, and open Russia to economic integration and improved relations with the international community—is highly improbable as long as Putin remains in power. The most probable outcome is that Putin will continue to escalate until he is defeated outright, removed from power, or offered concessions he can accept as victory.

The risk of horizontal escalation

Though it presents incredibly high risk, escalating the conflict beyond Ukraine’s borders in the near term is an option Putin could consider if his survival is at stake. A direct attack on NATO territory—perhaps through Lithuania to obtain a land corridor to the Kaliningrad exclave and cut off the Baltic States, should Russian forces find more success in Ukraine—is possible. The powerful Kaliningrad garrison, which includes nuclear-tipped Iskander-M and Kalibr systems, could assist. At sea, a desperate Russian Federation might attack and seize commercial shipping in international waters on the Black Sea and in the Baltic. Broadening the conflict to engage outside powers more directly might stop the flow of support and lethal aid to Ukraine, throw NATO into disarray, create openings for sanctions relief, and rally an increasingly disaffected Russian population. If tactical nuclear weapons are postured for use, or employed in desperation, the risks of uncontrolled escalation will become quite real. Such use is not likely, but cannot be ruled out.

Other military options also exist. Belarus has a substantial ground force of four heavy brigades, an airborne brigade, and strong artillery, which remain uncommitted. Putin could, in effect, take over and deploy this force in Ukraine or the Baltics, though its morale appears low. To distract and punish NATO for its support, hybrid operations in the Baltic States using Russian mercenaries, special-operations troops and intelligence paramilitaries from the Federal Security Service (FSB) and the Main Intelligence Directorate (GRU) could seize ethnically Russian parts of NATO territory (for example, in the Narva area in Estonia) and declare independence. While substantial Russian regular forces are not available in strength, this move would provoke frantic diplomatic activity in NATO and the EU, and could provide leverage for negotiations and sanctions relief.

Horizontal escalation in other regions—such as the Arctic, the Mediterranean, and the Far East—is also possible, but would suffer from the same disability: lack of military resources to achieve any decisive result. To date, Russian naval forces are intact and could be employed, but the Russian navy is not a true blue-water maritime force and, apart from nuisance attacks, could not realistically alter strategic outcomes. The same is true of Russian military aviation and space forces. Apart from generating confusion and a degree of misdirection, it is unlikely that these operations could contribute significantly to the success of the campaign in Ukraine, Putin’s principal goal. On the contrary, such operations could bring other military powers into the conflict against Russia, alienate others such as China and India, and change the correlation of forces decisively against Russia.           

“If Putin achieves a measure of success in Ukraine, however, horizontal escalation in the next 3–5 years is more likely.”

A US RC-135U flying in international airspace over the Baltic Sea was intercepted by a Russian SU-27 Flanker June 19, 2017. Due to the high rate of closure speed and poor control of the aircraft during the intercept, this interaction was determined to be unsafe. (Courtesy photo/Released)

If Putin achieves a measure of success in Ukraine, however, horizontal escalation in the next 3–5 years is more likely. Should the West decide not to provide offensive weapons or intervene directly, Putin can achieve a negotiated settlement, leaving Russia in possession of the Donbas, Crimea, and perhaps Mariupol, along with a pledge of Ukrainian neutrality. In this case, Putin would gain time to shore up his regime, rebuild his forces and economy, attempt yet again to develop a pro-Moscow regime in Kyiv, and pursue sanctions relief. Russian leaders will be mindful that, despite the devastation inflicted on Ukraine and concessions forced on it, Western leaders were not willing to confront Russia directly. The West will be seen as risk averse and subject to further rounds of intimidation. Hybrid approaches, with heavy emphasis on propaganda, subversion, disinformation and cyber operations, will figure prominently here.

Preventing and controlling escalation

What can NATO and the European Union do to prevent Russia from escalating the conflict to unacceptable levels? What follows are a few principles to guide NATO’s assessment of preventing and avoiding escalation.

Keep Ukraine in the fight. The first, and most immediate, curative is to keep Ukraine in the war. This means continued financial assistance, shipments of lethal aid, and real-time intelligence sharing, as well as humanitarian assistance and help with absorption and resettlement of refugees. The United States and Europe have shown unity and concerted action in responding swiftly to Russian aggression in Ukraine and this must continue, even as Putin seeks to find and drive wedges between transatlantic allies and partners. In this struggle, a coherent narrative, shared and articulated in common, will be critical.

In this regard, continuous references to the danger of escalation to “World War III” and a steady drumbeat of measures not to be taken can only serve to reassure Putin that he has a free hand in Ukraine. A degree of strategic ambiguity and the possibility of US and NATO intervention should he go too far can be helpful in moderating Russian excesses and controlling escalation. An “all measures on the table” approach will force Russian planners to consider, and prepare for, multiple response scenarios, complicating resource allocation and inducing uncertainty. While deterrence is more art than science, signaling to one’s opponent that one is too frightened to engage is more likely to encourage than to deter.

The most effective way to prevent spillover onto NATO territory and other forms of future Russian aggression is to help defeat Russian forces in the field inside Ukraine. Supplying Ukraine with food, fuel, spare parts, and modern equipment is the best way to do that, while still avoiding direct intervention by NATO. This means combat aircraft, main battle tanks, infantry fighting vehicles, self-propelled and rocket artillery, mobile air defense, secure radios, unmanned aerial vehicles, target-acquisition radars, spare parts, and ammunition, including precision-guided munitions. Many of these combat systems exist in storage in great numbers in the United States and in Europe. The Ukrainian military has shown remarkable versatility in adapting to unfamiliar systems such as the Javelin and Stinger, but exportable training packages, and even training sites in Europe for selected specialists, also warrant consideration.

If NATO intervenes, do it decisively. Several European nations, including Poland, Denmark, and Belgium, are considering some form of “peacekeeping” intervention in Ukraine, while calls for a no-fly zone are mounting as the civilian death toll rises. This suggests a critical mass of support may be forming for outside intervention under certain circumstances. Strong material and financial aid may enable Ukraine to hold on, and even advance to retake occupied territory, but Russia remains a far larger and stronger opponent. If the logic that it is better to defeat Putin in Ukraine than on NATO territory is sound, intervention to prevent the fall of Ukraine or its dismemberment must be considered. The prospect of actual genocide of Ukrainian civilians, or use of weapons of mass destruction, might also trigger NATO intervention.

This can take several forms. A no-fly zone would mean that NATO, or a coalition of the willing, employs combat aircraft based outside Ukraine to ground Russian military aviation, leaving ground combat to the Ukrainians (an analogy is the Kosovo air campaign). Unified command and control would be essential. The effort would fail if all targets required approval by thirty nations, so allowing discretion to military commanders acting within political guidance would be required. All Russian aircraft entering Ukrainian airspace would be engaged. Russian air defenses must be suppressed (perhaps even inside Russia), forward air controllers must be embedded with ground units to prevent fratricide, and target lists may be expanded quickly to include attack of Russian missile and rocket systems that are destroying Ukrainian cities.

A no-fly zone is, of course, an escalation itself, but one intended to lead to a Russian defeat in Ukraine to prevent follow-on aggression in Europe. Entering the conflict from the air is a serious and sober step. Some aircrew would be lost. Putin could retaliate by launching ballistic missiles against Polish, Romanian, or other European targets. To do so, however, would mean expanding the conflict against a much stronger and wealthier NATO, at a point at which almost all of Russia’s available combat power is deployed in Ukraine. Intervention from the air also provides a clear firebreak. Introduction of large NATO ground forces would be an even more dramatic step Russia would surely seek to avoid if possible.

Introduction of “peacekeeping forces” or establishing a “humanitarian no-conflict zone” in western Ukraine, use of NATO special forces and trainers, and deployment of “niche” specialists with critical skills such as communications, targeting, and computer-network defense are also forms of intervention that could contribute to success in Ukraine. Unlike air operations, however, these could make only marginal contributions that may not be worth the added risk of bringing the Alliance into the war. Should the campaign mature, and a no-fly zone materialize, these additional measures could augment Ukraine’s defense in helpful ways, but they should not precede air intervention. Direct intervention is a major step. It should not be undertaken except to achieve a decisive result.

Bolster forward presence. As a hedge against further Russian aggression and to reassure allies, the US deployed two additional heavy brigades to Poland in February and early March, along with an airborne brigade, bringing the US rotational “heel-to-toe” brigade there to divisional strength. US divisional and corps-level headquarters were also sent. The US 2nd Cavalry Regiment based in Germany (actually a Stryker brigade) was relocated to Romania at the same time. Additional air units and ground troops from a number of allies have also been deployed to NATO’s eastern flank, while the forty-thousand-soldier NATO Response Force (NRF) has been alerted for the first time in its history.

Putin’s rhetoric and aggressive disinformation and subversion efforts have, for years, targeted the Baltic States, which stand between Kaliningrad and contiguous Russia and extend almost to the suburbs of St. Petersburg. To forestall future aggression and cement firm deterrence, these forces should remain in eastern Europe at least for the near term (i.e., 3–5 years). As the campaign in Ukraine unfolds, Putin should understand clearly that NATO is postured to respond strongly to further escalation.

“Putin’s threats were intended to keep his neighbors weak, but recent events have proven that it is the perception of weakness, not strength, that provokes him most.”

The 51st Commando Battalion Romanian Special Forces run to an HH-60G Pave Hawk, assigned to the 56th Rescue Squadron, in Romania March, 9, 2022. (U.S. Air Force Photo by Senior Airman Noah Sudolcan)

For many years, policymakers have argued strenuously against providing the Baltic States, and NATO’s eastern flank in general, with an adequate defense for fear of “provoking” Russia and to “maintain Alliance unity.” Measures to build up Ukraine’s defensive capacity were resisted for the same reasons; the Barack Obama administration opposed lethal aid, even after the invasions of Crimea and the Donbas, while the Donald Trump administration provided only a trickle. The invasion of Ukraine has demonstrated the pitfalls of this thinking. Putin’s threats were intended to keep his neighbors weak, but recent events have proven that it is the perception of weakness, not strength, that provokes him most. Accordingly, a firm defense from the borders of Finnmark to the Black Sea can prevent spillover or regional escalation, communicate resolve, and reassure host-nation publics that the conflict in Ukraine will not land on their doorstep. This is under way with the recent announcement that NATO battlegroups will be posted in Romania, Bulgaria, Hungary, and Slovakia. Meanwhile, Germany, the United Kingdom (UK), Denmark, and others have also pledged to increase their forces in the Baltic States.

To further strengthen deterrence and head off escalation, NATO should thoughtfully consider how best to help the Baltic States help themselves. Though proud members of the 2-percent club, their small economies prevent them from acquiring the air defense and heavy forces they need to deter future Russian aggression. Estonia and Latvia field only a single light brigade each, while Lithuania fields a mechanized brigade with no tanks and a motorized brigade. Using security-assistance funds (such as the European Deterrence Initiative), the United States and NATO could equip existing Baltic formations with modern tanks, self-propelled artillery, and air defense from reserve stocks, along with the training, spare parts, and ammunition needed to make them viable. The Alliance should also strengthen the enhanced Forward Presence (eFP) formations in the Baltic States, as Secretary General Jens Stoltenberg has suggested. These forces are too small to pose a credible offensive threat, but can defend long enough for other NATO forces, such as the NRF and US armored units in Poland, to move up to assist.     

In the maritime domain, NATO’s naval strength clearly outmatches Russia’s, but operations in confined waters like the Baltic or Black Seas are complicated by land-based air and missile threats, as well as sea mines. Russian anti-ship missiles also outrange NATO’s. Should Russian naval forces begin to attack commercial shipping in international waters, NATO can respond with standoff weapons, but should exercise caution within range of land-based systems until they are suppressed. If Turkey agrees, stronger NATO naval forces should enter the Black Sea to provide flexible response options to counter Russian maritime aggression.

Take an unambiguous stance on nuclear policy. To relieve the threat of a Russian first-use nuclear strike and regain freedom of action, the United States and NATO must return to core deterrence principles. As it has for many decades, nuclear deterrence rests on both capability and credibility. NATO nuclear forces, though much reduced since the Cold War (especially with respect to theater nuclear systems) are redundant, survivable, and absolutely capable of destroying Russia from end to end. NATO’s credibility, on the other hand, is constantly undermined when leaders publicly express palpable fears that Putin will employ his nuclear arsenal, for unclear reasons and in unclear ways, and that they must at all costs avoid pushing him into a corner. A resolve not to be bullied is essential. Deterrence works best when leaders are direct, unambiguous, resolute, and calm, as John Kennedy was during the Cuban Missile Crisis. As President Emmanuel Macron reminded his public recently, the West has nuclear weapons, too.

Use economic tools as a primary “offensive” weapon. As the military campaign progresses, sanctions will continue to strangle the Russian economy. This pressure must continue—and, if possible, intensify—in order to force Russia, not just to the negotiating table, but to withdraw altogether from Ukrainian territory. To date, not all Russian banks have been banned from SWIFT, and many oligarchs remain unsanctioned. Though painful and difficult, weaning Europe from Russian energy, divesting from Russian businesses, and closing European markets are powerful weapons the EU can wield in its own right. (While 37 percent of Russian trade is with Europe, only 4 percent of the EU’s goods exports go to Russia.) Today, Russian energy remains exempt from EU sanctions. Developing alternate sources of energy, in particular, will take time and investment, but continued reliance on Russian oil and natural gas can only enable Putin to continue to finance the war in Ukraine.

In March 2022, the EU imposed its fourth tranche of trade sanctions on Russia, tightening export restrictions on dual-use technologies, expanding the list of sanctioned persons related to defense industries; imposing further trade restrictions for steel, iron, and luxury goods; and prohibiting transactions with specific state-owned enterprises. The challenge now will be to maintain the full range of sanctions until they bear fruit. Global food shortages, rising energy prices, and scarcities among certain commodities will challenge the sanctions regime. Much depends on the persistence and resolve of Western leaders.

Properly understood, comprehensive economic sanctions against Russia—what the French finance minister has called “total economic and financial war on Russia”—can be a major tool, denying Putin the financial resources to carry on the war and generating internal pressures on elites that could lead to his removal. By themselves, however, they will probably not end the war. China, Brazil, and India remain open markets and suppliers, if not active supporters, while Hungary and Serbia retain close ties. As former Deputy National Security Adviser General Rick Waddell has pointed out to the author, “An economy that is self-sufficient in energy and food takes a lot of killing.” In concert with diplomacy, aggressive information operations, and the military instrument of power, sanctions can be a vital component of an overall strategy to control and limit escalation and drive conflict termination by draining Russia of the financial resources it needs to carry on the war.

Prepare for the most likely area of escalation: cyberspace. As events progressively turn against Putin, the prospect of cyber war will loom ever larger, as it represents one of Russia’s most powerful remaining weapons. Few Western nations possess true offensive cyber capabilities, and the United States alone possesses the ability to deter major cyberattacks by delivering effective and large-scale reprisals. President Joe Biden has issued clear warnings to the private sector to harden its cyber defenses, which remain patchy and incomplete, and put Putin on notice that cyber assaults on critical infrastructure, the financial sector, and other key targets will be met with severe retaliation. A complicating factor is that cyber warfare on a strategic scale has never occurred, and much remains unknown about it. For example, attacks on critical Russian infrastructure, such as power grids and transportation networks, could unintentionally cause civilian deaths, while intrusion into military command-and-control nodes could alarm the commanders of Russia’s nuclear forces. In many respects, the cyber domain remains the realm of the unknown. Like aerial warfare in the early twentieth century, both sides must grope forward and learn as they go. A strong and clearly articulated cyber-deterrence regime, punctuated by sharp demonstrations if necessary, is the best defense here.

Maintain unity on the diplomatic front. In the midst of aggressive warfare, diplomacy may not capture the headlines. But, it must remain in play, above all because political objectives in the end must govern what happens on the battlefield. Here there are minefields. NATO and the EU may be tempted to intervene in negotiations and offer solutions—“off ramps” is au courant—to more quickly achieve a cessation of hostilities. These could take the form of sanctions relief and acknowledgement of Russian sovereignty over parts of Ukraine in exchange for “peace.” This would be a fatal error.

Practitioners of realpolitik may minimize Zelenskyy’s emphasis on shared values and the ongoing contest between democracy and autocracy, but his citizenry and millions in Europe and the United States won’t. Despite the leverage the West has over Ukraine as its storehouse and quartermaster, the Ukrainian people will decide “how this ends.” The political endgame—the definition of “victory”—must reflect outcomes they deem worthy of the enormous sacrifices they have made. The trap here is that Putin will not give up his aspirations if allowed to keep some of his gains, restore his finances, rebuild his forces, and try again.

The West has an opportunity to rule out that future altogether. That outcome rests on continued pressure, assistance to Ukraine, a resolute and united front, and the willingness to confront Russia decisively should Putin expand the conflict. Western diplomacy must be based on more than “stopping the fighting.” The United States and its allies must see through and beyond the endgame to a stable and lasting peace. That means the comprehensive defeat of the Russian military in Ukraine, before the conflict metastasizes further and spreads into Europe and beyond.

Throughout, diplomacy should leverage the strong, worldwide opposition to Russian aggression—as expressed in the UN General Assembly’s overwhelming vote of March 2—in all international forums. Traditional neutrals such as Sweden, Finland, and Austria have joined in strongly condemning Putin’s actions and have a growing voice. Building and sustaining this coalition should remain a top diplomatic priority.

“Western diplomacy must be based on more than “stopping the fighting.” The United States and its allies must see through and beyond the endgame to a stable and lasting peace.”

Left to right: US President Joe Biden with President Emmanuel Macron (France) and Boris Johnson (UK Prime Minister)

Summary recommendations

The outcome of Russia’s invasion of Ukraine is still uncertain. Much depends on a resolute response from the West. All courses of action carry risk, but the greatest risk is a settlement that leaves Putin with substantial gains and poised to commit further aggression after a period of retrenchment and recovery. To prevent this result and as laid out in more detail above, NATO and EU members should

  • agree on the defeat of Russia in Ukraine as the desired end state, vice a negotiated settlement that dismembers the Ukrainian state and allows Putin to claim success;
  • step up lethal aid to Ukraine, including the means to conduct offensive operations to recover occupied territory;
  • consider direct intervention if necessary to prevent massive civilian casualties or use of WMD;
  • maintain the presence of recent reinforcements on NATO’s eastern flank for the near term (3–5 years);
  • assist the Baltic States to strengthen their defense establishments with armor, air defense, and self-propelled artillery;
  • conduct recurring exercises from Finnmark to the Black Sea to enhance interoperability and forward presence;
  • strengthen tactical nuclear systems in Europe to enhance deterrence;
  • coordinate with Turkey for a stronger naval presence in the Black Sea;
  • sustain comprehensive economic sanctions until the desired end state is achieved;
  • implement a coordinated information campaign with a consistent and focused narrative;
  • harden computer-network defenses;
  • be prepared to conduct offensive cyber operations if required;
  • provide economic assistance and humanitarian relief;
  • reduce and eliminate dependence on Russian energy and rebuild energy security; and
  • conduct a sustained diplomatic effort, leveraging international organizations, to generate and maintain global pressure against Russia.


The Russian invasion of Ukraine is the most dangerous event to occur in Europe since the end of the Second World War. In its potential for enormous casualties, destruction on an epic scale, and escalation to unthinkable extremes, it demands the attention and considered action of NATO, the European Union, and the whole world. No one can see clearly exactly how the crisis will play out. This “strange voyage,” in Winston Churchill’s words, is a journey into the unknown, as all wars are. The best the West can do is prepare for the worst, keep its nerve, and employ all its resources when its vital interests and most cherished values are attacked. Things are very close to that stage now. At stake is an international order founded on something other than brute force, imperial ambition, and autocratic self-help. A Russian victory in Ukraine, even at great cost, places a vengeful Putin on Europe’s doorstep, his ambitions partially achieved but still unrealized. The next blow will fall on NATO’s eastern flank. Now is the time to ensure that never happens.


The Transatlantic Security Initiative shapes and influences the debate on the greatest security challenges facing the North Atlantic Alliance and its key partners.

Image: A service member of pro-Russian troops in a uniform without insignia drives an armoured vehicle in the separatist-controlled village of Bugas during Ukraine-Russia conflict in the Donetsk region, Ukraine March 6, 2022. REUTERS/Alexander Ermochenko TPX IMAGES OF THE DAY