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Issue Brief August 22, 2022

Sweden and Finland are on their way to NATO membership. Here’s what needs to happen next.

By John R. Deni

This post was updated on August 4.

Sweden and Finland have just cleared a big hurdle on their path to NATO membership with the US Senate’s overwhelming vote to welcome them into the Alliance. While several other allies still need to ratify the expansion, Finnish and Swedish membership in NATO is now not a question of whether but when.

Even though some analysts have posited that these two countries—especially Finland, which has an 830-mile border with Russia—bring disqualifying liabilities, most Alliance leaders, NATO-watchers, and European security experts argue these newest aspirants will strengthen the Alliance. This is especially so in terms of military capabilities and capacity, but also in terms of strategic culture and geostrategic outlook.

Nonetheless, in the days, weeks, and months after Finland and Sweden officially become members, there is an array of subsequent questions that these two aspirants, other allies, and NATO as an organization will need to consider—and ultimately answer. After examining the key strengths that Finland and Sweden are likely to bring into NATO, this issue brief will consider several of these critical topics. These include defense planning, operational planning, and readiness concerns.

Finnish and Swedish strengths

At roughly 131,000 square miles, Finland is one of Europe’s largest countries by area, yet, with just 5.5 million inhabitants, it is just the twenty-third largest by population on the continent. Together, these two datapoints indicate Finland’s population density is very low—just forty-two people per square mile.1By comparison, US population density is roughly ninety-four people per square mile, while Germany’s is 607 people per square mile. Defending such a large landmass with such a small population has never been easy for Finland, and the country has in fact only been independent since 1917, when it finally broke free of the crumbling Russian empire. Achieving and maintaining independence has meant that Finland relies on a small active-duty force—today numbering about 30,000 troops—backed up by a massive reserve of citizen-soldiers.2Reputable sources differ somewhat on the exact size of national military forces. For Finland, figures used in this policy brief come directly from publicly accessible Finnish defense ministry websites. For Sweden, the armed forces website features gross personnel numbers—personnel by military service are taken from The 2022 Military Balance (IISS, 2022). When fully mobilized, Finland can field a force of 280,000 personnel.3In contrast, and according to The Military Balance 2022, Norway has an active-duty force of just over 25,000 personnel and a reserve force of 40,000, while Denmark has an active-duty force of just over 15,000 and a reserve force of roughly 44,000.

The largest of Finland’s military services, the army, is comprised of about 22,000 active-duty troops. The Finnish army fields about a brigade’s worth of the advanced German-built Leopard 2A main battle tank, one of the best in the world and arguably better than the American M1A2 Abrams, the British Challenger 2, and the French Leclerc in terms of protection, firepower, and mobility. Finland’s army also has one of the strongest artillery forces in Europe, including the South Korean-built 155mm K9 self-propelled armored howitzers, one of the best in the world.

The Finnish navy is substantially smaller than the army, comprised of roughly 4,700 personnel and consisting primarily of smaller patrol and coastal surface combatants, mine warfare ships, amphibious landing craft, and logistic/support vessels. Recent upgrades to its Hamina-class missile boats will improve Finland’s ability to monitor and counter threats from the air, on the surface, and underwater. And although its Squadron 2020 procurement program has recently experienced delays, the Finnish navy will eventually replace seven older platforms—specifically a single Pohjanmaa minelayer, two Hameenmaa minelayers, and four Rauma missile boats—with four new multi-role corvette-sized surface combatants with ice breaking and mine warfare capabilities.

The Finnish air force is the smallest of the services at just over 3,000 active duty personnel, yet it may soon become the most technologically advanced of the three. In late 2021, Finland announced its intent to purchase sixty-four US-built F-35A fifth-generation fighters, joining nine other European members of NATO that will ultimately fly the radar-evading jet and allowing Finland to maintain a high degree of interoperability.4Those nine members of NATO are Belgium, Denmark, Germany, Greece, Italy, Norway, the Netherlands, Poland, and the United Kingdom. When Finland begins to take possession of the F-35s by 2026, it will also begin to phase out its current fleet of sixty-two F-18s, which it has flown since the mid-1990s.

The decision to purchase F-35s will raise Finland’s defense spending above 2 percent of gross domestic product (GDP), which is NATO’s agreed threshold for defense investment. Additional funding allocations—decided in the wake of Russia’s invasion—will increase this percentage still further over the next several years. Much of this funding will benefit Finland’s advanced but highly specialized defense industry. Several of its firms are world leaders in areas such as armored wheeled vehicles, turreted mortar systems, certain C4ISR/C5 systems, and logistical solutions.

Similarly, Sweden maintains a relatively small but capable and advanced military force, supported by its large, sophisticated defense industry and by its exceptional intelligence services, which have a long history of cooperation with the United States and other key Western partners. Since the early 2010s, Sweden has been rolling back downsizing decisions made in the aftermath of the Soviet Union’s collapse that affected nearly every service and capability.5Swedish intelligence services were a notable exception to the post-Cold War trend. Nonetheless, like many Western professional militaries, Swedish armed forces struggle to compete with more lucrative salaries offered in the private sector. As a result, its active-duty force remains somewhat small at just 14,600 troops.6This figure includes 2,950 logistics, intelligence, staff officers, and other active-duty military personnel. In addition to Sweden’s full-time active duty force, there are 20,100 part-time military personnel in the House Guard as well as 4,400 non-commissioned officers and enlisted personnel serving part-time in the armed forces. Conscription, which was only reinstated in 2018, has resulted in a reserve force of just 10,000, a fraction of the 200,000 available during the Cold War.

Regardless, the Swedish military has an array of advanced capabilities. In the land domain, the 7,000-strong Swedish army fields the German-built Leopard 2A main battle tank, the US-built Patriot air defense system, and Sweden’s own CV90 infantry fighting vehicle. Beyond this, Sweden’s land forces also have a wide range of capabilities including an airborne battalion; a chemical, biological, and nuclear defense company; two combat engineer battalions; and two artillery battalions. The last of these field the highly capable, self-propelled Archer 155mm artillery system, judged by some as one of the best in the world.

The Swedish air force, consisting of about 2,700 troops, is anchored by nearly one-hundred multi-role (and Swedish-built) JAS 39 Gripen jets. Reflecting the necessity of potentially fighting alone in austere, cold weather conditions, the Gripen was built to require little maintenance and to be capable of short takeoff and landing. As a result, its cost per flight hour is a fraction of the F-35, for instance.

The Swedish navy is the smallest of the three services with roughly 2,100 personnel, but it operates some of the most advanced equipment in the world. The Swedish-built Gotland diesel-electric submarine is the first non-nuclear-powered submarine to feature an air-independent propulsion system, extending its underwater endurance from a few days to weeks. Nonetheless, the Swedish navy, like the Finnish navy, is generally not a blue-water one—both countries’ naval forces are structured and equipped to operate largely in the Baltic Sea. This reflects the obvious threat perceptions and related security priorities of both Stockholm and Helsinki. Given the enduring nature of the Russian threat in the region, Alliance membership is unlikely to result in changes in this regard.

Unlike Finland, Sweden has yet to cross the 2 percent threshold for defense spending. However, the government in Stockholm approved a 40 percent increase in the defense budget for the 2021–2025 period, bringing total spending from $7.2 billion in 2022 to $11 billion by 2025 and marking the largest defense spending increase in seventy years. Sweden has also legislated an increase to its total mobilized end strength to 90,000 troops by 2025. Since Russia’s February 2022 invasion of Ukraine, Sweden’s center-left government has pledged even more funding for defense and announced its intent to reach the 2 percent target in the coming years, possibly as early as 2028.

Finally, both countries bring a keen understanding of and a long history of dealing with Russian rivalry and aggression. Given its historical claims to regional leadership, Sweden has been parrying Moscow for centuries. From the late fifteenth century through the early nineteenth, Sweden fought several wars against Russia. Although Sweden has been militarily nonaligned since then, it remained a rival of Russia in the Baltic region, including through the Cold War. Meanwhile, an independent Finland was born out of efforts to escape Russian domination in the early twentieth century. Since then, Finland has fought two wars against Moscow, experiences that have shaped its strategic culture and national security ever since. These historical experiences are likely to strengthen NATO’s approach toward Russia, stiffening its already solid resolve to resist Moscow’s influence and aggression.

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Alliance considerations

It is clear from their military capabilities that Sweden and Finland bring an array of key strengths to the NATO alliance. Their membership will also greatly complicate the job of Russian military planners tasked with developing offensive military scenarios anywhere in the Baltic region or the High North.

Despite these and other benefits of Finnish and Swedish membership, there are a variety of considerations NATO, its member states, Swedes, and Finns will need to weigh following accession. As any of NATO’s recent aspirants-turned-allies can attest, joining a large, complex intergovernmental military organization is not exactly a walk in the park. It is certainly true that Finland and Sweden are as close to NATO as any countries could be without being members. For example, representatives of both countries participate in nearly every routine meeting of the North Atlantic Council (NAC) at NATO Headquarters in Brussels, with some exceptions, such as meetings that pertain to nuclear matters or when the agenda includes the subject of NATO aspirants. Nevertheless, their accession raises a host of potentially difficult questions that all parties will need to address. The following sub-sections address the variety of issues at play and offer suggestions for policymakers.

Defense planning

As members of the Alliance, Finland and Sweden will participate in the quadrennial NATO Defence Planning Process (NDPP), which harmonizes defense planning among the allies by identifying types and quantity of forces necessary to undertake the Alliance’s full spectrum of missions. For many years, both Finland and Sweden have participated in the Planning and Review Process (PARP) under the auspices of NATO’s Partnership for Peace (PfP) initiative. The PARP is an entirely consensual process for willing partners aimed at cultivating interoperability and identifying capabilities that might be made available for NATO training, exercises, and operations. Under PARP, allies and partners together negotiate and set planning targets with a partner country, but the process is voluntary and not contentious.

In contrast, the NDPP is far more directive in nature and top-down driven. It is also the only Alliance process in which allies make decisions based on “consensus minus one.” After military capability target packages for each ally are developed by Allied Command Transformation, Allied Command Operations, and defense planners from the NATO International Staff and the NATO International Military Staff, a series of Multilateral Examinations occur. During these sessions, the allies review and agree on each target package on the basis of consensus minus one—the ally whose target package is the subject of the examination cannot veto what would otherwise be a unanimous decision by the rest of the allies.7Admittedly, if an ally objects to its target package, it only needs to convince one other ally to break the consensus. For this reason, collusion sometimes occurs, but it is typically limited to target packages involving technologically advanced military hardware, given the expense.

As with the routine NAC meetings, both Finland and Sweden have sat through several Multilateral Examinations as observers. However, being the focus of the meeting will likely prove somewhat more challenging than merely observing others going through the process. Beyond the examinations, the NDPP is sometimes contentious and generally far more intrusive than the PARP.

Moreover, from a substantive perspective, both countries will likely perceive an increased demand for capabilities and military capacity from the Alliance. Especially in terms of contributions to crisis management or expeditionary operations beyond the territory of the Alliance, Finland may perceive significantly increased demands, at least relative to what it has offered in recent years through the PARP. Its priority has been and must remain territorial defense of its lengthy border with Russia, but given its capabilities, capacity, and resources, it will surely be called upon to do more. For instance, given that Finland’s active-duty force is similar in size to Denmark’s, it is reasonable to assume that Finland might be asked to make available a mechanized battalion group, if not an entire mechanized infantry brigade, as was requested of Denmark in a recent iteration of the NDPP. Similarly, since Sweden’s active duty force is similar in size to Slovakia’s, it is reasonable to assume that Sweden might be asked to provide forces equivalent to a full armored brigade combat team plus NATO-compatible air defense capabilities as Slovakia was in the latest iteration of the NDPP.

Operational planning

Finland and Sweden each have a long history of cooperating with NATO allies—Finland since the early 1990s, and Sweden for far longer. This cooperation has occurred both bilaterally and multilaterally, and has included operational planning, deconfliction, and other forms of cooperation. Additionally, and especially since Russia’s first invasion of Ukraine in 2014, the two countries have coordinated closely with NATO on operations through or over their territory. In this way, they are far more advanced relative to other NATO aspirants of the last two decades.

However, there are several practical issues that both Sweden and Finland may wrestle with. For example, conducting day-to-day operations of the Alliance at its political headquarters in Brussels, its strategic commands in Mons and Norfolk, and across the rest of NATO’s bureaucracy will place much greater demands on Finnish and Swedish personnel. In addition to assigning Finns and Swedes to these international billets across Alliance bureaucracy, both countries will need to ramp up their national representation in various committees and other coordination venues throughout the Alliance. To some degree, Finns and Swedes are observers in many of these venues already, but the responsibilities and rights that come with membership will require more personnel to ensure the equities of Stockholm and Helsinki are adequately represented.

Based on similarly sized allies today, Finland and Sweden may need to provide as many as 150–200 additional staff officers, international civil servants, and national representatives. Both countries may need to build up to their potential somewhat slowly in this regard, as it likely means cultivating and developing an array of senior military and civilian experts capable of performing the necessary duties.

When it comes to the elements that comprise NATO Command Structure and NATO Force Structure, it seems clear that Finland and Sweden are not very interested—at least not yet—in hosting NATO infrastructure. While this may seem a reasonable accommodation to political realities, there are perhaps two key stipulations. The first pertains to command and control arrangements. If the Alliance is to extend Article 5 security guarantees, it will necessarily need to craft or modify a regional plan—perhaps in addition to those already under development—that includes the defense of Finland (and Sweden) in the event of a conventional military attack, at a minimum.

Among other things, NATO’s regional plans—like the Graduated Response Plans they will replace—should address the integration of host nation defense forces with NATO Response Force (NRF) elements, the new force model that may eventually replace it, as well as reinforcements from across the Alliance.8The new force model entails pre-positioning of more equipment, increasing air defense capacity and capability, earmarking specific forces to defend specific allies, and maintaining forces at higher levels of readiness. To facilitate integration of various forces and units, Finland might consider creating and hosting a multinational division headquarters to be designated as Multinational Division High North (MND-HN).9Ultimately, given the scale of Finland’s shared border with Russia and the array of forces likely necessary to defend it, Finland ought to consider expanding any MND-HN into a multinational corps headquarters. This command and control entity should primarily focus on the land domain, with appropriate air domain, electronic warfare, and special operations capabilities included, given the likely character of a Russian attack. Even though Finland currently lacks a peacetime division headquarters structure, it would make sense for Finland to build and lead such an entity given the size of its active and reserve land force, the scale of the defense challenge, and the unfamiliarity of most other allies with cold weather operations. For its part, Sweden might consider doing the same in the air domain, offering to establish a Combined Air Operations Centre for the High North (CAOC-HN) in addition to similar entities in Germany and Spain. This new CAOC-HN would have responsibility for planning, directing, and supporting air operations of allocated assets in both peacetime and crisis across the Baltic region, Scandinavia, and the High North.

However, to avoid the fatal flaws of NATO’s extant multinational headquarters and force structures—in which their multinational nature has inhibited both operational employment and operational effectiveness—several caveats are necessary. First, it is vital that any MND-HN or CAOC-HN be at least 85 percent manned by host nation personnel and therefore essentially dual-hatted as national assets capable of fulfilling Alliance requirements. Second, host nation personnel should take up the primary or deputy role in all headquarters staff sections. Finally, all non-host nation contributions to the crisis-time MND-HN and CAOC-HN structures—and for the purposes of routinely exercising during peacetime—must be at least brigade-sized or group/wing-size, given evidence regarding Alliance difficulties pushing interoperability to lower levels. The first two caveats would help ensure MND-HN or CAOC-HN can function if a contributing ally decides to prohibit its headquarters staff from participating in a particular operation and should enable them to appear as something other than strictly NATO infrastructure. The third caveat would help ensure that subordinate units are combat effective, in contrast to somewhat ineffective existing Frankenstein-like agglomerations of squads, squadrons, companies, and/or battalions from various allies. Initially, these objectives may prove a stretch for Finnish and Swedish manpower and leadership.

The second stipulation for the question of NATO infrastructure centers on the ability of both countries—but especially Finland, given its lengthy land border with Russia—to receive, stage, and integrate Alliance reinforcements in the event of a catastrophic attack. Both countries have signed memorandums of understanding regarding Host Nation Support with NATO, which allows for logistical support to allied forces located on or in transit through Finnish or Swedish territory during exercises or in a crisis. However, receiving large contingents of allied forces could exceed the capacity of existing Finnish and Swedish basing, transportation, and other logistical support, making it more difficult, if not impossible, to flow military forces into a conflict unfolding in the territory of either country. Recent efforts by NATO allies and partners to send military material to Ukraine have shown the importance of sufficient logistical capacity across the continent. Both Finland and Sweden, as well as the Alliance, should therefore consider three important mitigating steps.

First, both countries, but especially Finland, should consider establishing warm- or cold-basing facilities into which reinforcements would flow in the event of a crisis. For example, in the early 2000s, the United States established what it called a forward operating site at Mihail Kogalniceanu Airbase in Romania. This facility is relatively austere, but thanks to a skeleton permanent staff postured for turn-key operations, it has maintained the capacity to host a few thousand troops in short order as part of a “warm-basing” construct.10“MK” Airbase, as it is known, likely will soon become host to a rotationally deployed US Armored Brigade Combat Team (ABCT). In contrast, a “cold-basing” construct features similarly austere facilities but no permanent staff—additional time is therefore necessary to re-establish warm-basing or full operations. Ideally, warm- or cold-basing sites would be built near existing training areas and would be well connected to air, sea, and rail transportation nodes.

Second, both countries, but especially Sweden, should consider establishing prepositioned equipment sites. The US military maintains several prepositioned equipment sites in Europe, including in Belgium, Germany, Italy, the Netherlands, Norway, Poland, Spain, and the United Kingdom, and during its Madrid summit NATO allies decided to preposition ammunition and equipment in Eastern Europe. Having equipment—weapons, vehicles, ammunition, medical supplies, and so forth—available in the event of a conflict would make reinforcing Finland and Sweden much easier. This equipment should be kept up to date as military forces are modernized and the allies should regularly exercise drawing from and making use of these prepositioned stocks. Where conditions allow, hardened facilities built to withstand attack from Russian cruise and ballistic missiles should be built in Finland and Sweden to house this equipment. Finland and Sweden might benefit in this regard from tapping into NATO’s common budget for infrastructure, known as the NATO Security Investment Program (NSIP).

Third, the Alliance will likely need to conduct more in-depth analyses of logistical infrastructure necessary for large-scale reinforcement of or through Finland and Sweden. The relatively new Alliance logistics command—the NATO Joint Support and Enabling Command (JSEC)—could play a critical role here. Key issues to be examined include the extent of roll-on, roll-off port facilities capable of handling heavy forces; the weight capacity of key bridges and overpasses; and the condition, quality, capacity, and multi-modal interconnectedness of railways and roadways. The Alliance has gleaned some of this information already, when it has prepared for past exercises in Sweden or Finland, and it has had to think through many of the same issues in the Baltic states, but far more extensive data collection and analysis by logisticians will be necessary.


Like many countries already in NATO, Finland and Sweden have struggled in recent decades to build and maintain military readiness, in large measure because threats were perceived as far from home and certainly not existential. In some cases, especially when Swedish and Finnish military forces supported NATO operations in Afghanistan or elsewhere, military readiness was consumed as soon as it was built. This meant that even as they deployed highly capable, professional forces on expeditionary operations, both countries were limited in their ability to respond to unforeseen conflicts.

More recently, at least since the first Russian invasion of Ukraine in 2014, both Finland and Sweden have taken steps to increase readiness. Yet these efforts have met with mixed success. For example, “quick reaction” forces in Finland—the most prepared military forces—are minimal and generally limited to company-size formations comprised of twelve-month conscripts.11Although both Finland and Sweden allocate units to the NATO Response Force and the UK-led Joint Expeditionary Force (JEF), those allocated forces are not at the tip of the spear or among those prepared to deploy within hours or days—instead, these contributions are part of follow-on forces. Swedish military readiness is limited by shortcomings in their ability to retain trained troops with competitive pay and benefits, as well as the difficulty of rebuilding societal resilience and readiness, which was essentially eradicated after the Cold War and only reinstated in 2015. Additionally, although both are part of the NATO Response Force (NRF), they participate in supplementary, follow-on roles, not at the tip of the spear.

Moreover, although both countries have used exercises and extant operations, as in Afghanistan, to build interoperability with NATO forces, it is unclear how interoperable their reserve or territorial defense forces are with NATO. In the event of a serious, large-scale crisis, territorial defense or reserve forces of each country—especially among ground forces in Finland—would need to work very closely with NATO reinforcements. A lack of interoperability and familiarity with NATO procedures and practices could seriously undermine the coherency of any defense effort.

One way of addressing interoperability specifically and readiness more broadly is to dramatically scale up the number and scope of multinational exercises. Much is made of both countries’ “total defense” concepts and their resilience—and both Sweden and Finland can play important roles in propagating these concepts throughout NATO through exercises and other training events. Yet in Finland’s case, at least, military exercises involving anything larger than company-sized formations are uncommon. Routine Swedish military exercises are only somewhat larger, at battalion level. Larger exercises on a more routine basis will be necessary to ensure adequate readiness across active-duty, reserve, and multinational forces.

Additionally, the rest of NATO will need to give greater attention to cold weather operations in terms of exercises and training. Conducting operations in the High North will place unique demands on equipment, personnel, tactics, and readiness. Certainly, in contemplating the defense of northern Norway—a founding member of NATO—the Alliance has long had to consider and exercise under these challenging environmental conditions. However, with a much longer High North flank to defend than ever before, NATO will likely need to devote more of its readiness efforts toward addressing the unique requirements of cold weather operations.


The Alliance is likely to expand soon through the addition of Finland and Sweden. These two countries will bring advanced, capable military forces into the Alliance. Additionally, both will provide useful whole-of-society defense concepts, particularly given ongoing Russian hybrid attacks across the Alliance. Given their centuries-long experience in parrying Moscow, Finland and Sweden will also likely bring clear-eyed approaches to defense and deterrence. While some “southern tier” allies may chafe at the emphasis these new members will place on the threat posed by Russia, all members of the Alliance are likely to benefit over the medium- to long-term with Finland and Sweden at the table as full members.

Nonetheless, there is an array of issues that Finland, Sweden, current members of NATO, and the Alliance organization itself will need to wrestle with in the weeks and months after Helsinki and Stockholm come on board. Defense planning and capability development, operational planning for crises and contingencies, and readiness improvements are the most obvious areas in which hard work remains ahead.


The author wishes to thank several anonymous interviewees, including from the NATO International Staff and from the governments of Denmark, Estonia, Finland, Latvia, Lithuania, Norway, Sweden, and the United States. 

This issue brief is written and published in accordance with the Atlantic Council Policy on Intellectual Independence. The author is solely responsible for its analysis and recommendations. The Atlantic Council and its donors do not determine, nor do they necessarily endorse or advocate for, any of this issue brief’s conclusions.

This report was produced under the auspices of a project conducted in partnership with the Finnish Ministry of Defense focused on security and defense in the Nordic region.

John R. Deni is a research professor at the US Army War College’s Strategic Studies Institute and a nonresident senior fellow at the Atlantic Council. He’s the author of “NATO and Article 5.” The views expressed are his own.

The Transatlantic Security Initiative, in the Scowcroft Center for Strategy and Security, shapes and influences the debate on the greatest security challenges facing the North Atlantic Alliance and its key partners.

Image: Finnish soldiers take part in a mechanized exercise in Kankaanpaa, Finland, on May 4, 2022. Photo by Heikki Saukkomaa/Lehtikuva via REUTERS