US President Joe Biden has warned of Moscow’s “big mistake” while meeting leaders of nine countries on Russia’s doorstep.

Mr Biden discussed security with leaders of NATO’s eastern flank which he said were the “front line of our collective defence”.

He vowed that the US would defend “every inch” of the alliance’s territory.

Mr Biden said the Russian president had made a big mistake by suspending his country’s role in a nuclear arms treaty with the US.

The extraordinary meeting of the ‘Bucharest Nine’ in Poland, on the first anniversary of the Ukraine war, co-incided with Vladimir Putin leading a stadium rally in Moscow.

Gearing up the crowd, Mr Putin led chants of ‘Russia, Russia’ and gave a short address to bolster support at home for the war.

There were reports attendees had been offered payment to turn up.

Russian President Vladimir Putin at the Luzhniki Stadium in Moscow. Photo: Getty (Kremlin Press Handout)

Russia and China ‘deepen’ ties

Earlier Mr Putin met with China’s top diplomat Wang Yi.

In the highest level visit to Russia by a Chinese official since weeks before the invasion, Mr Wang told Mr Putin that his country was ready to “deepen” ties.

Mr Putin said he was looking forward to a visit to Moscow by Chinese President Xi Jinping and a stronger partnership.

Mr Xi is expected to make a “peace speech” on Friday.

Russia is due to begin military exercises with China in South Africa on Friday and has sent a frigate equipped with new generation hypersonic cruise missiles.

A Russian officer said on Wednesday that Russia would fire artillery but not the missiles, whose speed makes them difficult to shoot down.

On Wednesday (local time), Russia’s lower house of parliament rubber-stamped its suspension of the New START nuclear treaty.

Russia’s foreign and defence ministries have said they would continue abiding by the treaty’s restrictions on the number of nuclear warheads Russia could have deployed and the number of nuclear missile carriers.

Tension over Ukraine had already halted inspections under the treaty, which calls for the United States and Russia to let each other check their nuclear arsenals.