Rep. Seth Moulton (D-Mass.) says a nuclear war with Russia is a real possibility the U.S. should prepare for.

“For a long time, Russia and the United States had this sort of mutual agreement, mutually assured destruction,” he said Friday on CNN’s “New Day.”

“If they shot their weapons at us, we’d shoot our weapons at them, and therefore a nuclear war was unlikely to happen. But what Russia now says is that they will quote, ‘escalate to deescalate.’ They are willing to use nuclear weapons to deescalate a conventional attack. I think that the problem here is that we don’t really have a plan to deal with that.”

{mosads}Moulton said he can imagine scenarios where the Trump administration must respond to Russian use of nuclear weapons.

“If Russia starts using nukes against our allies in Europe, we may well use nukes in retaliation,” said Moulton, a member of the House Armed Services Committee.

“What if they target American troops — like the American troops who are training right now in Poland — with a nuclear attack?” he asked.

“What are we going to do and how quickly can that get out of control? That is why this is such a serious threat and why the Trump administration has got to take this more seriously.”

President Trump has frequently expressed openness toward warmer ties with Russian President Vladimir Putin.

The president said last month he wants the U.S. nuclear arsenal to be at “the top of the pack” worldwide.

“I am the first one that would like to see everybody — nobody have nukes, but we’re never going to fall behind any country, even if it’s a friendly country,” he told Reuters.