Russia's invasion of Ukraine has triggered the most serious crisis in relations between Russia and the West since the 1962 Cuban Missile Crisis, when many people feared the world was on the brink of nuclear war.

Medvedev cast the United States as an empire which had spilled blood across the world, citing the killing of Native Americans, US nuclear attacks on Japan and a host of wars ranging from Vietnam to Afghanistan.

Attempts to use courts or tribunals to investigate Russia's actions in Ukraine would, Medvedev said, be futile and risk global devastation.

"The idea of punishing a country that has one of the largest nuclear potentials is absurd. And potentially poses a threat to the existence of humanity," Medvedev, who now serves as deputy chairman of the Russian Security Council, said on Telegram.

Russia and the United States control about 90 per cent of the world's nuclear warheads, with around 4,000 warheads each in their military stockpiles, according to the Federation of American Scientists.

While president from 2008 to 2012, Medvedev presented himself as a reformer who wanted better relations with the West. But since President Vladimir Putin ordered the February 24 invasion, he has recast himself as a vociferous Kremlin hardliner.

"The whole of American history, starting with the conquest of the Native Indians, is a bloody war of annihilation," he said.

US President Joe Biden says Putin is a war criminal who launched an illegal invasion of Ukraine. The United States is supplying arms to Ukraine which says it is fighting for its survival.

Russia says what it calls "a special military operation" is intended to degrade the Ukrainian military and root out people it calls dangerous nationalists. Putin says the United States was using Ukraine to threaten Russia.

Medvedev said the United States had killed millions of people across the world since World War II.

Australian Associated Press