The U.S. president has promised Ukraine “whatever it takes, as long as it takes.” But out of anxiety about escalation, Washington is making decisions that could prolong the war.

"The language of escalation is the language of excuse.” That’s how Ukraine’s foreign minister, Dmytro Kuleba, dismisses anxiety that assistance to Ukraine could provoke Russia to either expand the war to NATO countries or cross the nuclear threshold. The country most concerned about Russia expanding its aggression beyond Ukraine is the country least likely to be the victim of it: the United States.

The Biden administration has been unequivocal in its policy declarations. The president has said, repeatedly and in public, that the U.S. will provide Ukraine “whatever it takes, as long as it takes.” The president wants the political benefits of heroically assisting the good of Ukraine against the evil of Russia, but his administration’s policy is much more hesitant than its bold declarations would suggest.

I spoke to Ukrainians both in and outside of government during a recent trip to Kyiv with the Renew Democracy Initiative. Those I met were keenly aware that Ukraine relies on U.S. weapons, U.S. financial assistance, and U.S. leadership to pull together international support, and they expressed gratitude for all that the United States is doing. Most know very well that Ukraine would have lost the war without the U.S. rallying support to keep its economy from collapsing, arm its soldiers, and provide essential intelligence to protect its leaders and blunt Russian attacks. Ukrainian government officials are careful to speak only of the United States as a whole, without singling out the Biden administration or delving into U.S. domestic politics.

Yet Ukraine’s foreign and defense ministers acknowledged that “the first answer the U.S. gives to any request is no.” That was America’s answer across the past three presidential administrations: no to javelin missiles, no to stinger missiles, no to NATO membership, no to F-16s, no to weapons that can reach Russian territory, no to tanks, no to Patriot air defenses, no to HIMARs, no to ATACMs, and—until this week—again no to F-16s, even if they aren’t U.S. F-16s.

The Biden administration has made three arguments against Ukrainian requests. The first and most condescending was, to quote the president, that “Ukraine doesn’t need F-16s now.” This came at a time when Russia’s strategy had shifted to long-range missile strikes on civilian populations and infrastructure that air dominance could better resist. Kyiv may now be well protected, but Kharkiv and other major cities continue to be at greater risk.

The Pentagon has further insisted that mastering the desired weapons systems would be prohibitively difficult and time-consuming. That argument weakened when Ukrainians, on a wartime footing, blew through the training curricula in a fraction of the time it took to train U.S. soldiers who had been in regular rotations on other systems. The Ukrainians have successfully sustained battlefield operability of an extensive array of internationally donated weapons systems.

The administration does make one argument against Ukrainian requests that should carry greater weight. Despite the president’s claims of unlimited assistance for as long as it takes, U.S. assistance isn’t endless, and Ukraine is asking for expensive items that are often in short supply. For example, having provided Ukraine with 20 HIMARs, the U.S. has only 410 remaining and 220 M270 MLRS (a tracked variant). That number may seem large, but not when you consider the intensity of fighting and the size of the U.S. forces that a war against China would entail. Nor are the costs inconsequential, even for the United States: An F-16 of the model Kyiv seeks costs about $15 million, and Ukraine wants 120 to protect its airspace. One reason the F-16 is Ukraine’s fighter of choice is that it exists in large supply in allied arsenals, not solely in the U.S. inventory.

The sweeping declaration that Washington will give Ukraine what it needs for as long as it takes is part of a pattern of presidential rhetorical largesse. It’s of a piece with committing U.S. troops to fight for Taiwan without providing the military budget to produce a war-winning military for that fight, or designing a national-security strategy that commits to allied solidarity while producing exclusionary economic policies that allies resent.

The escalation concern that looms largest for the Biden administration in Ukraine, understandably, is Russian nuclear use. Ukrainians remain admirably stalwart about this prospect, suggesting that a nuclear battlefield strike would not serve Russian objectives. To be more concerned about nuclear use than the likely victims of it are—or to push Ukraine toward untenable outcomes in the name of avoiding that risk—is to actually encourage nuclear threats. The United States can strengthen deterrence instead by publicly committing that if we see any sign that Russia is preparing to use a nuclear weapon, we’ll share the intelligence widely and provide Ukraine with weapons to preempt the attack. We can put Russia on notice that if it uses a nuclear weapon in Ukraine, we will send NATO radiological teams—NATO forces—there to assist Ukraine’s recovery, and we will ensure that any Russian involved in the decision or its execution ends up dead or in the Hague.

The true cost of the Biden administration’s focus on escalation may be one of prolonging the war. Former Defense Secretary Robert Gates has assessed that F-16s are “a decision that could have been made six months ago. Truth is, if they had begun training pilots on F-16s six months ago, then those pilots would be able to get into those airplanes this spring.” Our hesitance telegraphs to Russia that by continuing to assault Ukraine, it can wait us out—a lesson consistent with the course of the U.S. withdrawals from Iraq and Afghanistan.

For the leader of the free world to be more worried than the leaders of Poland, Denmark, France, Sweden, the Netherlands, and the United Kingdom is not a great look. Those countries are already considering offering fighters or training to Ukraine—and are at greater risk of Russian retaliation than the United States is.