Putin miscalculated his ability to invade Ukraine, says Biden

US President Joe Biden has said that he believed Russian President Vladimir Putin to be a "rational actor" who, however, misjudged his ability to invade Ukraine.

He added that Putin wrongly believed Ukrainians would submit to a Russian invasion.

He added that threats emanating from Russia could result in catastrophic "mistakes" and "miscalculations," but did not say how Washington would respond if Putin deploys a tactical nuclear device on the battlefield in Ukraine.

Biden also termed Putin's aims in Ukraine, which he spelt out in February during the start of the war, as ridiculous.

The President also ruled out meeting Putin at next month's Group of 20 summit in Indonesia. "I think he's committed war crimes. 

Biden added that he doesn't think the Russian President would use a tactical nuclear weapon on Ukraine.

Warned of potential errors in judgment that could ensue, Biden refused to disclose what a US response would look like should Putin follow through on his nuclear threats.

The President also said it was time to "rethink the US relationship with Saudi Arabia after the kingdom partnered with Russia to cut oil production. 

The Saudi-led OPEC+ oil cartel decided to cut production last week, angering the White House.