President Joe Biden told ABC News anchor David Muir in a new interview that it was a "big mistake" for Russian President Vladimir Putin to temporarily suspend Russia's participation in the last remaining nuclear arms treaty between the two countries.
"It's a big mistake to do that. Not very responsible. But I don't read into that that he's thinking of using nuclear weapons or anything like that," Biden told Muir in Poland on Wednesday, before the president flew back to Washington.
Biden said he was "not sure what else he [Putin] was able to say in his speech at the moment, but I think it's a mistake and I'm confident we'll be able to work it out."
Putin declared on Tuesday that Russia was suspending its participation in the New START treaty, first signed in 2010 and extended in 2021, which implements caps on the number of nuclear weapons deployed by each country and inspections of nuclear sites.
The Russian leader said that he was temporarily suspending participation in the agreement over support by the U.S. and other NATO allies for Ukraine, which has been fending off Moscow's brutal invasion for about a year.
"They want to inflict a 'strategic defeat' on us and try to get to our nuclear facilities at the same time," Putin said in a speech Tuesday, repeating a phrase American officials have used to describe their desired result in Ukraine.
Putin insisted that Russia was not withdrawing from the pact altogether, and the Russian Foreign Ministry said the nuclear weapons cap would still be respected. But the decision nonetheless dismayed Washington, with Secretary of State Antony Blinken on Tuesday calling it "deeply unfortunate and irresponsible."
"I think it matters that we continue to act responsibly in this area," Blinken told reporters. "It's also something the rest of the world expects of us."
Biden this week made a surprise visit to Kyiv, Ukraine, before rallying support among allies in Poland to keep up aid to the war-torn country.
"Appetites of the autocrat cannot be appeased; they must be opposed. Autocrats only understand one word, 'No!'" Biden said in Warsaw. "'No, no, no. You will not take my country. No, you will not take my freedom. No, you will not take my future.'"
For more from Muir's interview with President Biden, watch ABC's "World News Tonight with David Muir" at 6:30 p.m. ET.