US President Joe Biden has said American citizens should leave Ukraine immediately, Trend reports citing Sky News.
Speaking to NBC News, Biden added that he will not send troops to rescue US nationals from Ukraine if Russia invades.
He added: "We're dealing with one of the largest armies in the world."
"It's a very different situation and things could go crazy quickly."
When asked if there was a scenario that could prompt him to send troops to rescue Americans fleeing Ukraine, he replied: "There's not.
"That's a world war when Americans and Russia start shooting at one another.
"We're in a very different world than we've ever been."