MOSCOW, March 8 — Dmitry Medvedev, an ally of Russian President Vladimir Putin, called Joe Biden a "mad” disgrace to the United States today and said the US president had no right to compare himself to Franklin D. Roosevelt.

Biden opened his State of the Union address on Thursday with a reference to a 1941 speech to Congress in which Roosevelt said the union faced an unprecedented turning point in history.

Biden also accused Republican rival Donald Trump of kowtowing to Russia and, just over two weeks after calling Vladimir Putin a "crazy SOB”, said he had a message for the Russian President on Ukraine: "We will not walk away.”

"Even though Roosevelt was an infirm man in a wheelchair, he raised America from the Depression; Biden, on the other hand, is a mad, mentally disabled individual who set his mind on dragging humanity to hell,” Medvedev, a former president who is now deputy chairman of Russia’s Security Council, wrote on X.

"Roosevelt together with allies including the USSR, was fighting for peace; yet, Biden is actively and persistently trying to start WWIII.”

"Roosevelt was fighting against fascists, but Biden is fighting for them,” Medvedev wrote in English. "He is the United States’ disgrace!” Medvedev, who cast himself as a liberal moderniser when he was president from 2008-2012, now presents himself as an anti-Western Kremlin hawk. Diplomats say his views give an indication of thinking at the top levels of the Kremlin elite.

The war in Ukraine has triggered a deep crisis in Russia’s relations with the West, and Biden angered Russian officials with his "crazy SOB” comment. Putin, with an ironic smile, said the remark showed why the Kremlin felt Biden was a preferable future president to Trump.

Biden made that remark in a sentence about threats to the world including "that guy Putin and others,” the risk of nuclear conflict and the existential threat to humanity from climate change.

Putin portrays the US and its allies as a crumbling empire that wants to destroy Russia and steal its natural resources. — Reuters