Joe Biden urges American citizens in Ukraine should 'leave now'

US President Joe Biden on Thursday urged American citizens to leave Ukraine immediately, and warned about potential major conflict with Moscow should US and Russian troops engage each other on the ground.

"American citizens should leave, should leave now," Biden said in an interview with NBC News.

"We're dealing with one of the largest armies in the world. This is a very different situation and things could go crazy quickly," the president said.

Biden also reiterated that under no circumstances would he send US troops to Ukraine, even to rescue Americans in case of a Russian invasion.

"That's a world war. When Americans and Russians start shooting one another, we're in a very different world," he said.

Washington-Moscow tensions are at their highest since



the Cold War, with some US estimates saying some 130,000 Russian soldiers are grouped in dozens of combat brigades near the border with Ukraine.

Western leaders have been conducting shuttle diplomacy in an effort to ease frayed nerves. But Biden's comments -- and the State Department also on Thursday renewing its warning for Americans citizens to leave -- are almost certain to ramp up tensions anew.

Biden however dismissed the scenario of having to rescue Americans in Ukraine, saying "how do you even find them?"

"What I'm hoping is that if (Russian President Vladimir Putin) is foolish enough to go in, he's smart enough not to in fact do anything that would negatively impact American citizens."

Biden concluded saying that he would not have to tell that to Putin, adding: "he knows that."