US President Joe Biden has described Russia’s decision to suspend its participation in a landmark nuclear arms control treaty a “big mistake”.
His comments on Wednesday came as he met leaders of Nato’s eastern flank to show support for their security.
Mr Biden arrived in the Polish capital Warsaw late on Monday after a surprise visit to Kyiv just days ahead of the anniversary of Russia’s invasion of Ukraine, in February 24, 2022.
Amid the highest tension between Russia and the West since the Cold War over three decades ago, Mr Biden addressed thousands in Warsaw on Tuesday and said “autocrats” like Russian President Vladimir Putin must be opposed.
Hours earlier, Putin delivered lengthy remarks laden with criticism of Western powers, blaming them for the war in Ukraine. Mr Biden said the West was never plotting to attack Russia and the invasion was Putin’s choice.
Putin also backed away from the New START arms control treaty - a 2010 agreement that limits the number of Russian and US deployed strategic nuclear warheads - and warned that Moscow could resume nuclear tests.
“It is a big mistake,” Mr Biden said of Putin’s decision, as he headed into the meeting with eastern European allies.
Earlier on Wednesday, Mr Biden met staff from the US Embassy in Warsaw before gathering leaders of the Bucharest Nine - the countries on NATO’s eastern flank such as Poland, Bulgaria and Lithuania that joined the Western military alliance after being dominated by Moscow during the Cold War.
Most are among the strongest supporters of military aid to Ukraine, and officials from countries in the group have called for additional resources such as air defence systems.
At the opening of the meeting, Mr Biden reaffirmed US commitment to their security.
“As Nato’s eastern flank, you are the frontline of our collective defence,” he said.
“You know better than anyone what is at stake in this conflict. Not just for Ukraine, but for the freedom of democracies throughout Europe and around the world.”
He plans to discuss support for Ukraine before he returns to Washington.
The Kremlin says it regards Nato, which could soon expand to include Sweden and Finland, as an existential threat to Russia.
At Wednesday’s meeting, Romanian President Klaus Iohannis said the West should stand united in helping Ukraine. “We must continue to stand firm in delivering on our commitments to support Ukraine, as long as it needs to win this war,” he said.