U.S. President Joe Biden on Wednesday referred to his Russian counterpart Vladimir Putin as a "crazy SOB," a remark that triggered angry responses from the Kremlin.

"We have a crazy SOB like that guy Putin, and others, and we always have to worry about nuclear conflict, but the existential threat to humanity is climate," Biden said in a brief speech at the event in San Francisco that was attended by a small group of reporters.

In a hot mic slip in January 2022, Biden similarly called a Fox News journalist a "son of a bitch."

Biden's burst of strong language follows other occasions in which he has called the Russian president, who ordered the invasion of Ukraine in 2022, a "butcher" and a "war criminal."

Biden has said the United States will announce a package of tough new sanctions Friday against Russia over the death in prison of opposition leader Alexei Navalny.

'Hollywood cowboy'

The Kremlin, however, lashed out Thursday at the remark, saying it debased the United States, those who use such vocabulary and was a poor attempt to appear like a "Hollywood cowboy."

"The use of such language against the head of another state by the president of the United States is unlikely to infringe on our president, President Putin," Kremlin spokesman Dmitry Peskov said. "But it debases those who use such vocabulary."

Peskov said the remark was "probably some kind of attempt to look like a Hollywood cowboy. But honestly, I don't think it's possible."

"Has Mr. Putin ever used one crude word to address you? This has never happened. Therefore, I think that such vocabulary debases America itself," Peskov said.

He later added in comments to a state television reporter: "This is a disgrace for the country itself, I mean the United States."

Cold War 2.0

The war in Ukraine, the Navalny death and U.S. assertions that Russia plans to put a nuclear weapon in space have led to the biggest crisis in relations between Russia and the West since the Cold War.

Some Russian and U.S. diplomats say they do not remember a time when relations between the world's two biggest nuclear powers were worse, including during the 1962 Cuban Missile Crisis.

Biden said last week after prison officers announced Navalny's death in a Russian penal colony that it was "a consequence of something that Putin and his thugs did." Navalny had previously accused Putin of trying to kill him, an allegation the Kremlin denied.

Russian officials say the West rushed to blame Putin without waiting for evidence. The Kremlin says the West's reaction to Navalny's death is unacceptable and unjustified.

Biden said in a speech in Warsaw in 2022 that Putin "cannot remain in power." The White House played down the remark, while hardliners in Russia saw it as evidence that the U.S. wanted to topple Putin.

In 2021, Biden said he thought Putin was a killer. Putin said Biden phoned him later to give an explanation of why he used such words.