Families of US Embassy personnel living in Ukraine have been ordered to evacuate from Monday amid fears of an imminent invasion by Russian soldiers.
An official from the US State Department said Americans in the under-threat country were being urged to leave via flights - while they are still available, according to Fox News.
The update comes after more than 100,000 Russian troops, as well as equipment including tanks, were moved to the Ukrainian border.
Talks are continuing between Moscow and Washington to avoid any potential moves to cross the border, which could spark a full-scale war.
US Secretary of State Antony Blinken and Russian counterpart Sergei Lavrov are yet to make any breakthrough in a showdown in Geneva, Switzerland, but have agreed to keep trying to avoid a crisis.
This week President Biden warned he believes an attack is ‘imminent’, although he was criticised for hinting any response would depend on the severity.
Britain has sent troops and defence weapons to Ukraine and earlier today it was reported Russian defence minister Sergei Shoigu has accepted an invite to London to meet Defence Secretary Ben Wallace.
A senior defence source said: "The Defence Secretary is glad that Russia has accepted the invitation to talk with his counterpart.
"Given the last defence bilateral between our two countries took place in London in 2013, Russian defence minister Sergei Shoigu has offered to meet in Moscow instead.
"The Secretary of State has been clear that he will explore all avenues to achieve stability and a resolution to the Ukraine crisis. We are in communication with the Russian government."
It comes after Downing Street warned Russia would be "punished" if the country pushes ahead with any "destabilising action" in Ukraine.
Earlier, Foreign Secretary Liz Truss warned Putin he must "desist and step back" from war in Ukraine or risk being dragged into a prolonged conflict.
She said: "If there is an incursion by Russia into Ukraine, it would come at a massive cost.
"We are prepared to put very severe sanctions in place, we are also working to support Ukraine in terms of defensive capability."
Pictures released this week seemed to show a high number of troops and equipment being massed along Ukraine’s border as tensions heighten.
