Russia has the troops in place to invade Ukraine “at any time” and American citizens should leave within the next 48 hours, the US has warned.
An invasion could start with aerial bombing that would make departures difficult and endanger civilians, the White House said on Friday.
A host of other countries have also urged their nationals to leave Ukraine.
Russia has repeatedly denied any plans to invade Ukraine despite massing more than 100,000 troops near the border.
