Biden administration officials have warned Russian officials in private conversations of “catastrophic consequences” if Moscow uses nuclear weapons in its invasion of Ukraine, the U.S. national security adviser said on Sunday.
President Vladimir V. Putin of Russia said on Wednesday that he could use all arms available to him in the war — remarks interpreted by officials in both Russia and the West as a veiled threat about the use of nuclear weapons.
Jake Sullivan, the national security adviser, said in televised interviews on Sunday that the United States has detailed its potential response to the use of nuclear weapons to Russian officials, though he declined to make those details public.
Appearing on ABC’s “This Week,” Mr. Sullivan said the administration is taking Mr. Putin’s nuclear threats seriously — preparing for “every contingency” in the conflict and working to deter Russia from using nuclear weapons.
“We have communicated directly, privately, at very high levels to the Russians, that there will be catastrophic consequences if they use nuclear weapons in Ukraine,” Mr. Sullivan said.
On NBC’s “Meet the Press,” Mr. Sullivan said American and Russian officials have spoken frankly and repeatedly, including in recent days, about specific steps the administration would take if nuclear weapons were deployed.
“We do have the capacity to speak directly at senior levels and be clear about our messages to them,” he said, adding: “Russia understands very well what the United States would do in response to nuclear weapons use in Ukraine, because we have spelled it out for them.”
Also on NBC, Mr. Sullivan said there would be new announcements within the coming days of new economic sanctions from the Group of 7 nations against Russia — including on Russian entities operating in other countries — in response to Moscow’s “sham” referendums in portions of Ukraine it is occupying.
The voting, which ends early this week, is widely believed to be a pretext for Russia to annex those territories.
“We’ve been clear: We’re not going to stop or slow down our support to the Ukrainians, no matter what Putin tries to do with these fake elections and fake referenda and annexation,” Mr. Sullivan said on CBS News’s “Face the Nation.”
Ukrainian and Western officials believe that the rushed voting would open the door for Mr. Putin to claim that Kyiv’s defensive war was an attack on Russian territory.
On Sunday, President Volodymyr Zelensky of Ukraine reiterated that annexation by Moscow would scuttle any fleeting hopes for a diplomatic resolution to the crisis.
Mr. Sullivan put it even more bluntly, citing plunging Russian troop morale and shortages of precision-guided weapons.
“What we are seeing are signs of unbelievable struggle among the Russians,” Mr. Sullivan said.
“You’ve got low morale, where the soldiers don’t want to fight, and who can blame them because they want no part of Putin’s war conquest.”
He continued: “You’ve got Russia disorganized and losing territory to a capable Ukrainian force. And you’ve got a huge amount of infighting among the Russian military leadership. And now the blame game has started to include these replacements.”