Russia’s war against Ukraine is a system-transforming conflict that is reconfiguring the geostrategic picture in Europe and in Asia. It is also fueling a debate in the US defense policy community about how to structure and posture US forces. For the United States and its NATO allies, there are big lessons from this war that are already circulating through the policy bloodstream, but those lessons are encountering serious headwinds generated by what has been establishment thinking over the past three decades. Recent years of “scheduled wars,” fought on the US timeline with cross-domain control and unchallenged logistics, have changed expectations of what the US military would need when it comes to readiness levels and equipment to fight current and future wars.

The overarching lesson from the unfolding war in Ukraine is simply the scale of what’s required to fight a modern state-on-state war. No Western military has prepared for such levels of weapons and munitions consumption and force attrition. No NATO ally today—save for the United States—has the armor or munitions stocks that could last longer than a few weeks or months at best on Ukraine-like battlefields. This war has brought front and center the enduring centrality of mass in modern conventional warfare with a near-peer adversary. It should also put paid to the obsession with precision strikes that has dominated the US defense acquisition culture in recent years.

This war has brought into focus an enduring truth in warfare: In a state-on-state conflict, mass trumps precision. The impact of mass is immediate and registers at the point of contact, while precision strikes on enemy forces concentrated in the rear, on ammo depots, or on logistical chains will only register over time, perhaps after the decision on the battlefield has already been reached. True, space can compensate for mass to an extent, but none of NATO’s flank countries has the advantage of geography to plan accordingly in the event of a Russian invasion, nor would the Indo-Pacific region offer favorable space in terms of terrain should China decide to invade Taiwan.

The United States needs to embrace the old principles of mass and redundancies that paved the way to victory in World War II and allowed it to successfully deter and ultimately defeat the Soviet Union during the Cold War. The war in Ukraine continues to show that one’s military needs mass to counter the adversary’s mass—a reality that has been all but absent from US thinking about the nature of warfare since the end of the Cold War. Since the early 1990s, a fundamental structural change took place in US military thinking about its force structure, especially the US Army. The Army acquired an “Air Force mindset,” whereby ever-greater technological sophistication sought to compensate for reductions in numbers, in effect altering what used to be the bread and butter of the American way of war. 

The war in Ukraine has shown that one needs mass to counter mass. When it comes to numbers, you need to match or, better still, outmatch what your enemy can field. During World War II, for example, Germany had tanks that were in many ways superior to US tanks in design, but in the end those Tigers and Panthers were outmatched by the sheer number of the Shermans the United States could field.

There is, then, something to be said for old-fashioned systems in a future conventional combat against a near-peer adversary. While technology gives Western forces an edge, that edge will only go so far when confronted with sheer numbers. If NATO ends up at war with Russia or if the United States and its allies in Asia end up in a war with China, then the decisive factor may be manpower and production elasticity when it comes to weapons and munitions. In a protracted conflict, the decisive factor could be the capacity to reconstitute forces—both personnel and equipment—to compensate for those that have been attritted on the battlefield. And here an excessive fascination with ever more complex systems could play against the United States. It will need to replenish losses faster than its adversary, which is likely to be producing simpler and cheaper systems.

The principle of mass applies to personnel, too. The United States and its allies also should question if the current model is well suited to generating large standing armies of the kind needed should they be pulled into a major conventional war with Russia or China, or both. 

There is also a larger geostrategic dimension that ought to factor how to structure and posture US and NATO forces in Europe, especially along the eastern flank. The entry of Finland and (soon) Sweden into NATO has redefined the geostrategic environment in Europe, shifting the center of gravity in NATO into Central and Northeastern Europe. Still, when it comes to fielding large forces, only two countries along the Nordic-Baltic-Black Sea “intermarium” corridor command the requisite populations to do so. One of them—Poland—is a NATO ally, while the other—Ukraine—aspires to become one. Other countries along this corridor lack the populations needed to field large armies. While Finland, with its system of territorial defense and military training, can field a force of some 280,000 in an emergency, its small population of 5.5 million doesn’t augur well for long-term sustainment. 

This is one more reason why bringing Ukraine into NATO is not just about reaffirming the core values the Alliance is built on; rather, it is first and foremost about the fundamentals of power and mass that will be needed to build an effective deterrent posture against future Russian aggression. Simply put, Poland and Ukraine—once the latter has been brought into the Alliance—will be the core of NATO’s restructured deterrent and defense posture along the eastern flank. The United States should start by permanently stationing at a minimum three Brigade Combat Teams—two in Poland, another in the Baltic States—while continuing to provide the nuclear umbrella and high-end enablers. The Scandinavians, Finns, Balts, and Romanians could then complete the wall of steel, while allies further west, especially Germany, could provide the requisite depth and sustainment. Reconfiguring NATO’s eastern flank in this way would make any effort by Russia to invade further into Europe an impossible proposition. 

The West is facing a revanchist Russian state intent on relitigating the outcome of the Cold War and restoring its imperial sphere of influence. Russia has already effectively reabsorbed Belarus and has its sights firmly set on Ukraine—and possibly beyond. Hence, the conflict in Ukraine carries with it a high risk of horizontal escalation that could spark a wider war in Europe. If the United States and NATO go back to the basics of permanent forward basing and mass, Russia will be deterred. And if Russian President Vladimir Putin or his successor dares to cross the line, such an incursion by Russia would be decisively defeated.

Andrew A. Michta is the director of the Scowcroft Strategy Initiative and senior fellow at the Atlantic Council.

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Image: Tank crew are seen as they take part in a military exercise in the training centre of Ukrainian Ground Forces near Goncharivske in Chernihiv region, Ukraine, September 10, 2016. REUTERS/Gleb Garanich