In response to the Russian invasion of Ukraine in February 2022, the United States has increased military spending, NATO has expanded, and the West has embarked on a military buildup. Though Russia’s invasion was provocative and unwarranted, many of these steps are unnecessary and some are even unwise.

First, both Putin and outside observers overestimated the Russian military at the outset of the war, and it will be even weaker by the end of the war—especially if Russia is to retain any territory in Ukraine as part of a negotiated settlement, as Rajan Menon’s essay proposes. In the months before the Russian invasion of Ukraine, and during the first week of the invasion, many observers expected an immediate and crushing Ukrainian defeat. The forces arrayed on each side seemed woefully lopsided: the war, if it could be called that, would be a repeat, in some respects, of the swift fall of Ukraine’s Crimea region to Russian paramilitary and military forces in late February 2014.

Others were not so sure. In mid-January 2022 the historian Timothy Snyder wrote, “The forces that Russia has deployed are capable of a terrifying level of destruction. But invading Ukraine would also be an incredibly stupid move by Russia. . . . It would probably feel a lot like the Soviet invasion of Afghanistan in 1979: seemingly successful at first, then system-destroying after a few years.”

And, as is common in authoritarian states, no one wanted to tell the boss that his troops were unprepared or that the operation would be difficult. Optimism about the virtues of military offensives is a common characteristic of armed forces. Further, the West has consistently overestimated Russian, and before that Soviet, military power. Throughout the Cold War, threat inflation led to various gaps—including the “bomber gap,” the “missile gap,” and the “throw-weight gap.” Since the invasion the parlous state of Russian military forces has become evident. They have had logistical issues from the outset of the war, running out of food, fuel, and ammunition. They have chewed through tens of thousands of troops—220,000 killed and injured by late March 2023—and been forced to make not one, but two call-ups of hundreds of thousands of more troops and to hire mercenaries.

The military buildup by the United States and Europeans is an overreaction.

If the Russians are defeated and pushed back to Crimea or even removed entirely from Ukraine, their army will be greatly weakened. If they win some territory, and attempt to keep it, they will be even weaker, as they may have to spend more blood and treasure to defend any gains. Second, the military buildup by the United States and Europeans is an overreaction and may leave a legacy of increased military spending, armament, and potential superpower rivalry and instability.

To be sure, several elements of the Western response to the Russian invasion were prudent. Specifically the economic sanctions against Russia were wise, and it is important that they hold. Sanctions probably never work by changing an adversary’s mind, but they can deprive a country of much needed cash or equipment and the effort to bypass or bust sanctions can be expensive. Depriving Russia of revenue to prosecute this war is essential. Over the long run, whatever can be done to decrease dependence on Russian fossil fuels will be useful. Further, NATO allies and the United States, in particular, have given both military equipment and economic support to Ukraine. This equipment—including anti-tank weapons—has been vital for the Ukrainians. Perhaps even more important is the high quality of the U.S. intelligence that allows Ukrainian armed forces to skillfully meet and anticipate Russian forces. The European Union has also provided Ukraine with funding for weapons and other assistance.

But NATO has also increased military spending and enlarged the alliance, with Finland joining in April, the fastest ever accession in NATO’s history. Germany has already increased military spending and promised an even larger increase with their next budget. Moreover, according to polling about 62 percent of Germans would support an even larger investment in the German military. While these steps show solidarity with Ukraine and are politically popular, they are not militarily necessary. The NATO alliance was already vastly superior to the Russian military.

The enlargement of NATO and the increased acquisition of military equipment by the alliance and other counties exceeds current needs to replace weapons donated or sold to Ukraine and sets NATO up for future spending and arms acquisition—even after the war ends. Combined with nuclear modernization and the escalating war of words with China, the United States and the West are on the path not only of ever-increasing military spending, but the potential for arms racing and nuclear instability.

Third, less expensive and less provocative military doctrines could and should be considered instead. A lower conflict outcome would include the arms control and confidence building mechanisms that Menon mentions.

Immediately after Russia’s invasion of Ukraine, Russian troops made significant advances, quickly stalled, and were eventually turned back, losing most of the territory they had taken. In those first weeks, Ukraine’s less well-equipped military had not yet received most of the thousands of anti-tank and anti-air weapons, helicopters, armored personnel carriers, and so on that would flow over the next several months. But their success gave Ukraine vital time to get organized and get millions of people out of harm’s way.

The Ukrainian military prepared for war against a much stronger adversary and also mobilized the civilian population to resist.

How did the Ukrainians hold against the Russians at the outset of the war? The tremendous intelligence information coming from the United States and United Kingdom was critical, as was the equipment and training that the United States had already provided. The Ukrainian military also had experience since 2014 in fighting against the Russian military and advance notice of the Russian build-up. But the Ukrainian defense doctrine was perhaps as important. The Ukrainian military prepared for war against a much stronger adversary and also mobilized the civilian population to resist. In the weeks following the invasion, Ukrainian civilians famously switched or removed highway signs to slow and misdirect the Russian advance on the ground. And these were not spontaneous acts. The Ukrainian government had already begun to make their civil society more resilient to attack. As CNN reported last year, the Ukrainian government promoted both violent and nonviolent resistance tactics:

Early in the conflict, the Ukrainian government created a website that explains different ways to resist. The site describes ways of using nonviolent actions, including boycotting public events, labor strikes, and even how to use humor and satire. The goal is to disrupt the ability of pro-Russian authorities to govern while reminding the population of Ukraine’s rightful sovereignty. The resistance doctrine suggests violent actions as well, including using Molotov cocktails, deliberately starting fires and putting chemicals in gas tanks to sabotage enemy vehicles.

Thus the lesson of Ukraine may be that large militaries can be bogged down, their advances frustrated, and occupation made difficult, if not impossible, with relatively less expensive defensive equipment combined with civilian resistance tactics and civil society resilience. In other words, a defensive military doctrine that relies on the advantages of home territory and short-range weapons can work. Nothing about this alternative is certain. There are technical challenges, and we need to know much more about what a successful doctrine would look like. We would also need arms control and confidence building measures in addition to restructuring military doctrines. But, given the costs and risks of the present course, what used to be called “non-offensive defense” or “defensive defense” may well be a viable alternative to current offensive doctrines.