One of the most dangerous conclusions that America’s political and policy elites took away from the West’s victory in the Cold War is that deterrence not only can work, but if applied with military strength and emphatic rhetorical resolve, it always will work. The current generation of U.S. foreign policy practitioners now appears determined to apply that simplistic “lesson” to Washington’s relations with both Russia and China. That attitude has already created alarming tensions with those two major powers, as the United States repeatedly adopts measures that intrude on their core security interests. If US policymakers don’t adopt a more restrained approach, the outcome could well be armed conflicts with nuclear implications. The current crisis between the United States and Russia regarding Ukraine is especially worrisome, and it is a textbook example of Washington’s warped perspective.

The members of America’s foreign policy establishment invariably assume that credible deterrence consists of two components. One is maintaining quantitative and qualitative US military superiority. If the United States deploys sufficient military assets to a theater to protect its own interests or those of an ally, the reasoning goes, a potential adversary will not challenge that force, knowing that such an effort would almost certainly fail — and do so with disastrous consequences for the “aggressor.” The other key element of credible deterrence, according to the conventional wisdom, is to make Washington’s determination to thwart aggression against itself or an ally emphatically clear, so that a challenging power understands that the US commitment is not a bluff, but is instead deadly serious.

Those points are valid — as far they go. However, they fail to capture the nuances, complexities, and limitations inherent in a policy of deterrence. Advocates of belligerent policies toward Russia especially seem to miss two crucial considerations. First, the actual credibility of Washington’s stance on any issue depends heavily on the importance of the stakes involved to the United States compared to their importance to a potential adversary. Second, even if Washington continues to enjoy undisputed military superiority on a global basis, it doesn’t necessarily mean that it has such superiority in a specific geographic theater.

US policymakers are badly misreading the situation in Eastern Europe with respect to both considerations. The Biden administration is intensifying its willingness to back Kiev’s policies and treat Ukraine as a NATO member in all but name. Erasing that distinction has serious implications. Under Article 5 of the North Atlantic Treaty, the United States has an explicit obligation to assist another member if it is attacked; there is no such obligation to non-members. Yet just days ago, Secretary of State Antony Blinken again insisted that Washington’s commitment to Ukraine’s “territorial integrity” is “unwavering,” and he warned Moscow against continuing the buildup of Russian military forces near the border with its neighbor.

Blinken and other administration officials apparently assume that such a declaration will dissuade the Kremlin from taking military action. However, Moscow’s behavior has been more a reaction to aggressive moves that the United States and its Ukrainian client have already taken than it is evidence of offensive intent. Russian leaders have viewed the steady expansion of NATO’s membership and military presence eastward toward Russia’s border since the late 1990s suspiciously and they have considered Washington’s growing strategic love affair with Kiev as especially provocative.

Ukraine’s own policies have become dangerously bellicose. The government’s official security doctrine adopted earlier this year, for example, focuses on retaking Crimea, the peninsula that Russia annexed in 2014 following the West’s campaign that helped demonstrators overthrow Ukraine’s elected, pro-Russian president. Statements by President Volodymyr Zelensky and other leaders have been disturbingly bellicose, and Ukraine’s own military deployments have further destabilized an already fragile situation.

US hawks are pushing to increase Washington’s implicit commitment to defend Ukraine, again assuming that such moves would cause Russia to cower. The Wall Street Journal’s editorial board asserts that the best way to convey the message of unwavering US support would be to provide “more lethal military assistance to Ukraine, whose troops are fighting and dying against Russian-backed separatists in the east.” Western backing also should include a “surge of NATO troops” to neighboring Poland. To enhance NATO’s deterrence throughout Eastern Europe, Lexington Institute analyst Dan Goure recommends permanently deploying US combat units in that region, creating the ultimate tripwire that would supposedly deter Moscow from making any aggressive military moves.

Such proposals ignore how seriously Russia regards Ukraine in its own security calculations. Yet the Kremlin has issued repeated warnings to the United States and NATO that incorporating Ukraine into the Alliance would cross a red line. In late November, Vladimir Putin renewed that warning, making it clear that Moscow would regard the presence of any NATO troops or weapons in Ukraine as intolerable.

It should be obvious that Ukraine is much more important to Russia than it is to the United States or other Western countries. Moscow seems determined to prevent Washington from making Ukraine a forward staging area for NATO military power directed against Russia. That position is entirely credible. If Ukraine becomes a NATO front-line state, Moscow loses any buffer between NATO and the Russian homeland, with among other consequences, then having to defend a 1,500-mile border from encroachment by the most powerful military alliance in the history of the world. An already beleaguered great power might well be willing to go to war to prevent such an outcome. Given the imbalance of US and Russian interests in Ukraine, the situation is ripe for a US deterrence failure. Whatever Western officials may say, there is inevitable doubt that the United States and NATO would really go to war to defend Ukraine, since it would be self-destructive folly to do so.

A sober calculation of the military situation also should induce greater US caution. The outcome of a fight between Russia and Ukraine without US/NATO intervention would be a foregone conclusion. Granted, there is no question that the United States is much stronger than Russia militarily on an overall basis. The disparity in military spending levels between the two countries alone makes that outcome inevitable. Washington’s current budget is more than $733 billion, while Russia’s comes in at a far more modest $61.7 billion. Although Russia is increasingly able to deploy some units with state-of-the-art weaponry, the United States enjoys a significant qualitative edge as well.

However, unless the United States and its allies are willing to wage an all-out war against Russia, an armed conflict confined to Ukraine (and perhaps some adjacent territories), would diminish much of that advantage. Russian forces would be operating close to home, with relatively short supply and communications lines. US forces would be operating far from home with extremely stressed lines. In other words, there is no certainty that the US would prevail in such a conflict. Russian leaders likely have reached a similar conclusion, and that factor also reduces the credibility of US/NATO deterrence regarding an intervention on Ukraine’s behalf.

In short, Washington may be issuing security promissory notes to Ukraine that it is not capable of redeeming at anything faintly resembling a reasonable level of cost and risk. No rational person wants a nuclear war with Russia over Ukraine’s status, but short of that, the U.S.-led effort at deterrence lacks credibility. Both in terms of the importance of the issues at stake and the balance of conventional military power in the immediate area, the advantage goes to Russia. Such a situation creates a textbook scenario for a probable deterrence failure.