If Russia Drops a Nuke, the U.S. Has These Three Options

In the unlikely but not impossible event that Vladimir Putin follows up on his recent threats and drops a nuclear bomb on Ukraine, the U.S. will have only a handful of feasible options for response.

"The most important thing is the U.S. would want to try to deter Putin from doing that [using a nuclear weapon]," political scientist and former CIA officer Matthew Kroenig told Newsweek.

"And that's what the administration has been trying to do over the past week or so.... But if [Putin] does go ahead and use nuclear weapons, then it's the U.S. that's in a difficult position," he said.

The Russian president's recent threat about using nuclear weapons to defend Russia against attack might be more than just bluffing, as Putin himself said on September 21 during a speech announcing a partial mobilization of reservists in his country. On October 2, Defense Secretary Lloyd Austin said that U.S. officials were considering possible responses to a Russian escalation of the Ukraine war into a nuclear conflict, but he did not reveal what these might be.

What Possible Responses Are Available to the U.S.?

Should the U.S. deterrence strategy fail for any reason—possibly because Putin feels cornered and lacks any other options for appearing triumphant in the Ukraine war—then the Biden administration should execute its deterrence threat, according to Kroenig.

"I think the Biden administration probably hasn't made up its mind yet and probably wouldn't make up their mind until nuclear weapons are actually used," he said about a U.S. response.

"I think some in the administration would say, 'Well, let's just do a tougher version of what we're doing already. More sanctions. More weapons to Ukraine. Maybe more forward-deployed forces in NATO countries.' And they would argue [that] this...be a tougher response than what we're doing now."

In this first scenario, according to Kroenig, "Biden avoids a war with Russia." But he believes that many, including himself, would argue that this reaction isn't strong enough.

"We spoke of catastrophic consequences and then we respond with sanctions—that's a weak response," he said. This response would send the message to Putin that he can launch a second, third and fourth nuclear attack without consequences.

"I would advocate a direct U.S. conventional military attack against Russia," Kroenig said. "And that could be directly against the forces that launched the attack. It could be against other Russian military targets in Ukraine or in the Black Sea."

In this second scenario, a third world war might be triggered, as a U.S. strike on Russia might cause Moscow to retaliate. "And does Biden retaliate to that? And then we're off to a major conflict, and that is a possibility," Kroenig said.

It's likely a third response will also be advocated, he said.

"I think you might get U.S. strategic men saying, 'Mr. President, nuclear weapons have been used for the first time since World War II. People have always assumed that we would respond with nuclear weapons to a nuclear attack. We need to use nuclear weapons in response to restoring nuclear deterrence.'

"I'm guessing President Biden would not go that route, at least initially, but I think some in the room might be advocating for that," Kroenig said.

In this third scenario, the U.S. responds to a nuclear attack with another one, triggering a nuclear war.

Will Putin Launch a Nuclear Strike In Ukraine?

Speaking to CNN on October 2, Austin said there is no way of knowing whether Putin will follow through with his nuclear threat. "There are no checks on Mr. Putin," he said. "He made the irresponsible decision to invade Ukraine. He could make another decision."

Experts agree.

"It's more likely than not that [Putin] does not launch a strike, but there is a real risk he might," Kroenig said.

He continued: "I don't think this is an easy decision for Putin. I think he is on the fence. I think on one hand he is worried that using nuclear weapons could lead to a major U.S. and NATO response that he would prefer to avoid. On the other hand, he's losing this important war right on his border. And I think he sees both strategic and military utility to using nuclear weapons to turn the tide of the war. So I think he hasn't made up his mind yet."

"What makes sense is to threaten NATO and Ukraine," Marina Miron, who is with the Defense Studies Department at King's College London, told Newsweek.

"There is a psychological element to this all," she said. "The threat of use of nuclear weapons creates fear. And that is the effect that the Kremlin is seeking to exploit. We have seen it in the past on numerous occasions, and we are seeing it now. The Russian leadership might be many things, but suicidal is not one of them. That said, there is always a possibility of human and/or machine error."

At the moment, most observers think it's unlikely that Moscow will drop a nuke, especially as dissent appears to be growing in Russia amid Western sanctions and military defeats in Ukraine.

But "because of the extreme consequences of the use of any nuclear weapon, any risk has to be taken very, very seriously," John Erath, senior policy director for the Center for Arms Control and Non-Proliferation, a U.S.-based nonprofit, told Newsweek.

"The risk of the use of a nuclear weapon is small, but it is perhaps greater than it has been at any point since the Cold War," he said.

Erath said he believes now is the time "to prevent the attacks before they happen."

"I think it's the time for very careful messaging and very active diplomacy to make sure that the Russian government is hearing from all possible sides that it would not be a good idea to use nuclear weapons, that they will not get what they are trying to achieve through the use of nuclear weapons, and that there will be severe consequences should they go ahead and do that. In this way, we can best try to prevent any such weapon from being used," he said.

The problem is that Putin has made a threat, and "if you make a threat, you have to be prepared to follow through on it, otherwise it's worthless," Erath said. And if Putin is feeling desperate, he might get to the point of using a nuclear weapon, even if doing so won't change the situation on the battlefields in Ukraine.

Newsweek has contacted the Pentagon for comment.