Biden to meet eastern Nato allies in wake of Putin's nuclear warning

US President Joe Biden will meet leaders of Nato's eastern flank on Wednesday to show support for their security after Moscow suspended a landmark nuclear arms control treaty.

Biden arrived in Warsaw late on Monday after a surprise visit to Kyiv just days ahead of the anniversary of Russia's invasion of Ukraine on Feb 24, 2022.

During the period of highest tension between Russia and the West in the decades since the Cold War, Biden addressed thousands in downtown Warsaw on Tuesday and said "autocrats" like Russian President Vladimir Putin must be opposed.

Hours earlier, Putin delivered lengthy remarks laden with criticism of the Western powers, blaming them for the war in Ukraine. Putin also backed away from the New START arms control treaty and warned that Moscow could resume nuclear tests.

On Wednesday, Biden will meet staff from the US embassy in Warsaw before gathering leaders of the Bucharest Nine, the countries on Nato's eastern flank who 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 meeting, Biden plans to reaffirm commitments over their security and discuss support for Ukraine before he returns to Washington.

Russia regards Nato, which could soon expand to include Sweden and Finland, as an existential threat.

Lithuanian President Gitanas Nauseda's message to Biden will be that it wants "greater involvement of the US in Europe, Nato's eastern flank and, of course, more aid to Ukraine," his chief foreign policy adviser told Lithuanian radio on Tuesday.

"Lithuania and other like-minded countries have several requests, which concern air defence, forward defence presence, air defence systems, and greater investments in the defence industry," Asta Skaisgiryte said.

The former Soviet republic on Russia's doorstep joined Nato in 2004 and plans to host Biden in July for the security alliance's leaders' summit.