▶ Watch Video: Russian drills with Belarus escalate Ukraine tensions

The State Department is asking Americans in Ukraine to leave the country immediately, issuing a Level 4 travel advisory on Thursday. The advisory warned Americans not to travel to Ukraine and for those in Ukraine to leave “due to the increased threats of Russian military action.”

“There are continued reports of a Russian military build-up on the border with Ukraine, indicating potential for significant military action against Ukraine,” said the advisory. “The security conditions, particularly along Ukraine’s borders, in Russia-occupied Crimea, and in Russia-controlled eastern Ukraine, are unpredictable and can deteriorate with little notice.”

The State Department warned that the government would not be able to evacuate Americans if Russia invades and urged for Americans in the country to come up with contingency plans that do not rely on assistance from the U.S. government.

“American citizens should leave now,” President Biden told NBC News on Thursday. “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.”

In January, the State Department authorized the voluntary departure of U.S. direct hire employees  and ordered the departure of eligible family members from the embassy in Kyiv.

The warning cited Crimea and areas of Donetsk and Luhansk as areas of increased risk .U.S. government officials are prohibited from traveling in Russia-occupied Crimea, citing that
“authorities continue to abuse and arbitrarily imprison foreigners and the local population.”

Tensions are high in the region with Russia amassing more than 100,00 troops surrounding the border of Ukraine. The Pentagon believes Russia now has 70% of the forces in place to mount a full-scale invasion of Ukraine. If Russia invades, it would be the largest conflict in Europe since World War II.

Russia on Thursday kicked off military exercises with Belarus along the Ukrainian border, leading to NATO increasing its own forces in the region.

CBS News has confirmed that the U.S. government has plans in place to evacuate the thousands of Americans living in Ukraine — if it needs to do so — to neighboring Poland, a NATO ally to which the U.S. has recently deployed additional troops.

David Martin and Christina Ruffini contributed to this report. 

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