President Joe Biden asked any Americans in Ukraine to ‘leave the country now’. His statement comes as NATO forces are headed to the alliance’s eastern borders, UK is putting 1,000 troops on standby and Russia has concentrated more than 100,000 troops near Ukrainian borders. 

In an interview with NBC News host Lester Holt, Biden admitted that ‘things could go crazy quickly’. 

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“American citizens should leave now. It’s not like we’re dealing with a terrorist organization. We’re dealing with one of the largest armies in the world. It’s a very different situation, and things could go crazy quickly,” he said.

Asked whether there was any scenario that would prompt him to send US troops to Ukraine to rescue Americans, the president added, “There’s not. That’s a world war when Americans and Russia start shooting at one another.”

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“We’re in a very different world than we’ve ever been,” he continued.

He argued that if Putin is “foolish enough to go in, he’s smart enough not to, in fact, do anything that would negatively impact on American citizens.”

Asked whether he’s ever said that to Putin, Biden said he had.

“I didn’t have to tell him that. I’ve spoken about that. He knows that,” Biden said.

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Meanwhile, the State Department issued an advisory warning that the US ‘will not be able to evacuate its citizens in the event of Russian military action anywhere in Ukraine’. 

British Prime Minister Boris Johnson said that the Ukraine crisis has grown into “the most dangerous moment” for Europe in decades. 

“I would say in the course of the next few days, in what is the biggest security crisis that Europe has faced for decades, and we’ve got to get it right,” Johnson said at NATO headquarters in Brussels.

With inputs from the Associated Press