The reality is that as Mr. Putin’s failing military skedaddles east across occupied Ukraine, nuclear weapons look more attractive. That is not so much because a tactical nuclear strike would be effective against widely scattered Ukrainian forces in the field. It is more that Mr. Putin hopes the political shock waves set off by nuclear explosions in Europe would shatter the West’s resolve to support Ukraine. Is Germany willing to lose Berlin to save Kyiv? Are Americans ready to risk New York to keep Odessa free? These are the questions Mr. Putin is asking himself.
The future of the world may depend on his answers. Meanwhile, the Biden administration faces a terrible dilemma. To yield to Mr. Putin’s nuclear blackmail would be a cowardly act of appeasement from which Neville Chamberlain would recoil—and which would open the door to more nuclear blackmail. Yet to lead the Western alliance into an open-ended nuclear confrontation with Russia is to risk the most catastrophic of wars.
To avoid these unacceptable alternatives, the Biden administration must deter Mr. Putin from using nuclear weapons in the Ukraine conflict even as it continues to support Ukraine in its battle to drive the invaders back.
Deterrence is more complicated than it looks, and the Biden administration’s efforts to deter Russia have had little success. In February, Mr. Putin blew past the Biden administration’s barrage of threats and diplomacy to launch the war in Ukraine.
Not deterring Russian aggression was one of the costliest failures in recent American foreign policy. But it isn’t clear that the Biden administration understands what went wrong—and how similar mistakes might be undercutting its diplomatic efforts today.
Unintentionally and unwittingly, the administration sent Russia mixed messages last winter. On the one hand, a dramatic burst of diplomacy worked to coordinate a broad Western response to the potential invasion, with Europeans joining Americans in threatening severe sanctions. Biden officials broke with precedent to declassify and publicize highly sensitive information about Mr. Putin’s plans in ways that dramatically undercut Russia’s official statements and propaganda. That intelligence helped build Western unity in the face of the Russian attack, and Biden officials are right to take credit for this unorthodox but effective campaign.
At the same time, however, senior American policy makers seriously overestimated Russia’s military strength and acumen. As storm clouds gathered over Kyiv, U.S. officials ordered all senior American diplomats to evacuate. They also urged allies to evacuate and offered Volodymyr Zelensky an airplane to flee.
This was hardly a message of deterrence. As the Russian leader finalized his preparations, the evident American belief in the invasion’s success would, if anything, have eased any doubts Mr. Putin might have felt. Further, since the Biden administration had reassured the Russians that American combat troops would not engage in any Ukrainian war, Mr. Putin did not need to worry about a powerful, immediate American military response.
We will have to do better this time if we expect to deter him from using nuclear weapons. Mr. Putin already knows that fear of a Russian nuclear response has affected American and allied policy. We have limited Ukraine’s access to long-range missile systems that could hit Russian territory. Other North Atlantic Treaty Organization allies, including Germany, have made similar calculations.
From Mr. Putin’s point of view, in a war in which almost everything is going wrong, nuclear blackmail is working. Why wouldn’t he double down on the one tactic that works?
The only way to deter any possible use of nuclear weapons is to make Mr. Putin believe that the consequences of such use will be ruinous for Russia as a state and for him as its ruler, and that the West won’t flinch when the time for action comes.
To make his threats credible, Mr. Biden needs, first, to make up his mind that he is prepared to stay the course. “The double-minded man is unstable in all his ways," the Bible tells us. Facing down Mr. Putin in a nuclear standoff is not a course for a man who lacks conviction.
If Mr. Biden is sure of himself, he must build an ironclad coalition at home and abroad behind those threats. Rather than playing down the danger, he needs to dramatize it. Making a prime-time speech to the country, addressing a joint session of Congress, holding an emergency NATO summit—these can all demonstrate Mr. Biden’s commitment to respond with overwhelming force to Russian nuclear attacks.
While Americans won’t unanimously support this policy, most responsible people in both parties recognize Mr. Putin’s Russia as a threat to American security and world peace. A broad show of national unity on this issue will send a sobering message to Moscow.
Deterring Russia doesn’t mean humiliating it. As President Kennedy understood, deterrence complements diplomacy. The more effective our deterrence, the more flexible our diplomacy can become. Deterrence however comes first. Mr. Biden must bar the door to using nuclear weapons before he can seek a path to peace.
