"We have a son of a mad dog, like Putin." Biden

At a fundraiser in San Francisco on Wednesday, US President Joe Biden called Russian President Vladimir Putin a "crazy bastard," warning that the threat of nuclear conflict is always there. Still, the existential threat to humanity remains the climate.

"Climate is the last existential threat. We have a madman like Putin and others, and we always have to worry about nuclear conflict. But the ontological threat to humanity is the climate," Biden said.

Biden's verbal attacks on Putin have also sharply escalated in the White House and campaign trail. Last week, the US president blamed Putin and "his gang" for the death of opposition leader Alexei Navalny.