US President Joe Biden has criticized Russian President Vladimir Putin, saying he has totally misjudged his ability to invade Ukraine.

In an exclusive CNN interview on Tuesday, Biden said, "I think he is a rational actor who has miscalculated significantly." The president indicated that Putin did not expect the invasion to last so long.

Biden reiterated his criticism of the Russian leader for unilaterally announcing the annexation of four Ukrainian regions.

Biden said Putin's claim that "he was needed to be the leader of Russia that united all of Russian speakers" was "irrational."

When asked whether Putin would use a tactical nuclear weapon, Biden said he doesn't think so, but he criticized Putin for talking about the possibility.

Biden said, "I think it's irresponsible for him to talk about it, the idea that a world leader of one of the largest nuclear powers in the world says he may use a tactical weapon in Ukraine."