US nationals should immediately leave Ukraine, the US embassy in the country said in a statement, APA reports citing TASS.
"The security situation in Ukraine continues to be unpredictable due to the increased threats of Russian military action. Conditions may deteriorate with little notice. US citizens in Ukraine should depart immediately using commercial or other privately available transportation options", the statement reads.
"US citizens may now enter Poland across the land border with Ukraine. No advanced approval is required," the embassy said, adding that it had opened a welcome center near the border "to provide assistance to US citizens entering Poland from Ukraine."