The Kremlin accused US President Joe Biden of behaving like a "Hollywood cowboy" after he called Russian President Vladimir Putin a "crazy SOB" at a campaign event.
During a speech in San Francisco on Wednesday evening, Biden referred to Putin as a "crazy SOB," according to members of the press travelling with him - the abbreviation stands for "son of a bitch."
Biden was talking about climate change as an existential threat to humanity to a small group of campaign donors when he made the comment, only mentioning Putin in passing.
"This is the last existential threat, it is climate. 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," the 81-year-old said.
On Thursday, Putin's spokesman Dmitry Peskov said his boss was impervious to the insult and then took a swipe of his own at Biden.
"Such boorish statements from the mouth of a US leader are hardly capable of hurting the head of another state in any way, much less President Putin. But it is a great shame for the country itself," Peskov said, according to state news agency TASS.
"It is clear that Mr Biden is demonstrating Hollywood cowboy behavior to serve domestic political interests," Peskov continued.
Former Russian president Dmitry Medvedev, who is a close ally of Putin and now serves as deputy chairman of the Security Council of Russia, delivered a harsher assessment of Biden.
"As opposed to what the US president has said, the existential threat is not climate; but the useless old geezers, like Biden himself, who have become senile and are ready to start war against Russia," Medvedev said.
The Democrat, who is seeking a second term in the presidential election in November, has used the expletive before.
When a reporter from Fox News threw a rhetorical question at the president in January 2022 on the sidelines of a public appearance in Washington, Biden muttered for all to hear, as his microphone was still switched on: "What a stupid son of a bitch."
