Russia is reengaging in the eastern flatlands and southern littorals, and security assistance to Ukraine is intensifying. But as Vladimir Putin’s war enters a more protracted phase, the West should also begin preparing for the post-war security environment — because while the war is primarily about Ukraine’s future, it has also proven that inertia will not be enough to deter another failure of Western strategy.

How should the alliance adapt? Fortunately, Western leaders have an excellent remedial guide in Future War, coauthored by two retired US generals (including CEPA’s own Ben Hodges) and a leading British strategist with over a century’s combined practical and academic experience.

Their recommendations derive from two key assessments. First, the emerging security environment will contain multiple threats — chiefly Russia and China, but also instability to Europe’s south and borderless hybrid tactics — at a time when US strategic dominance is eroding. Limited US resources will increasingly flow towards the Indo-Pacific, even as the Kremlin poses an enduring threat. In a worst-case scenario, simultaneous crises in distant theaters — in Taiwan and along NATO’s eastern flank, for example — would almost certainly demand resources beyond capacity, and present impossible choices.

Second, emerging and disruptive technologies (EDTs) could fundamentally change the character of warfare. By virtue of the speed of AI-enabled systems, humans could soon be excluded from the decision-making cycle. This would introduce another degree of uncertainty into the security environment: the military balance would mirror the rapidity of technological innovation, not the gradual pace of traditional capability development. Inherently uneven EDT investment and application across the alliance could also engender interoperability gaps with potentially decisive operational implications.

The coauthors worry that these trends portend trouble for the West. But instead of decoupling North America and Europe — in essence, leaving Europeans to defend themselves so the US can focus on China — Future War argues that the alliance should remain the West’s defensive center of gravity. Striking a strategic balance commensurate with the threat will require creative thinking: trading space for time by exercising the transition from contested peace to all-out conflict, making preparations to receive US strategic heavy forces, considering a more forward-based presence along the eastern flank, and preparing for high-tech warfare.

Putin’s war strengthens their argument. It demonstrates that Putin’s Russia cannot be parked, only managed. This is not to diminish China, the pacing threat — but pivoting to the Indo-Pacific without a sustainable, forward-looking deterrence plan for Europe is merely hope disguised as strategy. This would invite future tests of Western capabilities and resolve, prevent the West from sequencing crises, and cede an opportunity to deter war in Europe and enable US competition elsewhere. As Thomas Schelling famously argued, the US presence in Europe has an outsized deterrent effect; it need not diminish capacity elsewhere. A strategy organized around the threat environment can and should flow from the transatlantic alliance.

Putin’s war is also a reminder of the costs of war — and the importance of allies. Ukraine’s skill, bravery, and morale are the primary reason that Russian forces might culminate in the coming months. This turn of events would have been impossible without Western security assistance. It has also come at a tragic and continuing cost to Ukraine, which speaks to the importance of allies in tilting the military balance and mitigating the intangible factors of warfare. It also underscores the costs of failed deterrence: drain the color from images of Bucha, Mariupol, or Kyiv and many are indistinguishable from the wars of the last century. The line between unprecedented prosperity and the brutality of war is thin.

So as the West prepares for the emerging security environment, it should keep allies close by building cohesion in concrete ways — including through regular consultation, coordination, and exercising. Alliances are the product of consistency, not immediacy. The US cannot expect Europe’s support vis-à-vis China if it does not continue to cultivate its 70-year investment.

Future War was a prescient call-to-arms upon publication last year. In response to Putin’s war, the alliance rallied. It regained some of its urgency and sensibility to tragedy. While ‘future war’ ironically looks much like previous ones — dominated by the mass and steel of heavy equipment rather than drone swarms and weightless cyberstrikes — the emerging security environment will require further rapid and forward-looking adaptation. We must hope that the alliance does not lose momentum before this adaptation is complete.

Carsten Schmiedl is a NATO 2030 Global Fellow. He was previously an analyst with the Center for European Policy Analysis (CEPA) and advisor to the co-chair of the 2020 NATO Reflection Group.