At a May 3 NATO change-of-command ceremony, Secretary of Defense Ash Carter questioned the Kremlin’s tactic of nuclear saber-rattling. Moscow’s jarring rhetoric about nuclear weapons aims to intimidate the West. It has led to unwise suggestions for how the United States and NATO should respond, ideas that should be ignored. Carter, however, should go beyond what he said and more specifically rebut the Russian leadership’s misguided notion of nuclear brinksmanship.

In parallel with its aggression against Ukraine, the Kremlin has sought to rattle the West, including with nuclear threats. President Vladimir Putin regularly talks about Russia as a nuclear superpower, even bizarrely suggesting that he was prepared to go on a nuclear alert when the Russian military seized Crimea in 2014. His loose talk emboldened the Russian ambassador in Denmark last year to threaten to target that country with nuclear weapons.

Carter said that such saber-rattling “raises troubling questions about Russia’s leaders’ commitment to strategic stability, their respect for norms against the use of nuclear weapons, and whether they respect the profound caution that nuclear-age leaders showed with regard to brandishing nuclear weapons.”

Such Russian rhetoric is worrisome, particularly in view of Russia’s modernization of its tactical nuclear arsenal and its “escalate to de-escalate” doctrine. That doctrine raises a question about whether the Russian military might think it could successfully employ a small number of low-yield nuclear weapons in a bid to end a conflict on terms favorable to Moscow.

That, in turn, raises questions for NATO and how it should respond. When alliance leaders meet in Warsaw in July, however, they will face a full agenda: Ukraine, bolstering NATO’s conventional defense capabilities and helping to address instability on Europe’s southern flank. Leaders will likely have little bandwidth to address nuclear posture questions.

That posture is based on U.S. and British strategic nuclear forces, which provide the ultimate guarantor of NATO security. Some two hundred U.S. B61 nuclear bombs in Europe help symbolize the American commitment to the alliance’s defense. The United States does not need to add to its nuclear capabilities on the continent (and, indeed, in calmer times the U.S. military could and should have reduced its nuclear presence).

Some, however, have suggested deployment of new nuclear arms in Europe or redeploying B61 bombs from their current locations to central European countries, such as Poland. Neither idea has merit.

First, NATO’s European members show little appetite for hosting new American nuclear arms. Second, moving B61 bombs to central Europe—and closer to Russia—would be expensive and have the undesired effect of making the bombs and their delivery aircraft far more vulnerable to preemption in a crisis. Moreover, it would be hugely provocative (think 1962 and the Soviet basing of missiles in Cuba). Many allies would question Washington’s common sense.

NATO does not need additional nuclear arms to meet Russia’s challenge. The alliance has long viewed tactical nuclear weapons more for their political value than for their military utility. Its doctrine eschews the notion of fighting a tactical nuclear war, something no ally would welcome. If ever used, the main purpose of the B61 bombs would be to send a political signal, a warning that the situation was about to spin out of control, including possibly to use of strategic nuclear weapons.

While the United States and NATO do not need additional nuclear weapons in Europe, they should try to steer the Russian leadership away from any idea that it might resort to nuclear arms at low or manageable risk.

Here is where the secretary of defense should come in. It is time for a major speech on nuclear deterrence to answer and rebut the loose words coming from Moscow. Carter has grappled with the issues and challenges posed by nuclear weaponry for most of his professional life. No one could better lay out the risks of any nuclear use or the perils of clumsy nuclear brinksmanship.

Carter could use his speech to stress the point that a nuclear weapon is a nuclear weapon, period. No one should think that employment of a low-yield nuclear weapon (or a few) would somehow be different. Even a small nuclear bomb would cross the nuclear threshold—a threshold that has not been breached for more than seventy years—and would open a Pandora’s box of unpredictable and potentially dire consequences.

This is a message that Putin and Moscow need to hear. NATO does not want the Kremlin to somehow convince itself that a “small” nuclear conflict would be manageable. It is time to start disabusing the Russian leadership of the notion that its nuclear saber-rattling is a safe, acceptable or successful tactic.

Steven Pifer is a senior fellow at the Brookings Institution.

Image: Kremlin.ru