WASHINGTON, Jan 25: The US has asked American citizens in Ukraine, including its employees at the embassy in Kyiv and their families, to leave Ukraine immediately as they may face security threat as Russia is mobilising its military at the border for an invasion.

The State Department stated that the security situation in Ukraine is deteriorating as the extraordinary deployment of Russian forces and equipment to its border has been going on for several months, it said.

The British Foreign Office said it had evidence that Russia wants to install a friendly Government in Ukraine. It said Kremlin is seeking to replace Ukraine’s Government with a pro-Moscow administration under former Ukrainian legislator Yevheniy Murayev.

“Our recommendation to US citizens currently in Ukraine is that they should consider departing now using commercial or privately available transportation options,” a State Department official told reporters on Sunday evening.

“The security conditions, particularly along Ukraine’s border and in Russian- occupied Crimea and in Russia-controlled eastern Ukraine are unpredictable and can deteriorate with little notice,” the official was quoted as saying.

With a view to averting a fresh confrontation in the region, Foreign Ministers of the US and Russia have held several rounds of talks. President Joe Biden and Russian President Vladimir Putin also have had virtual meetings in the recent past.

Secretary of State Antony Blinken told his Russian counterpart Sergei Lavrov at their meeting in Geneva on Friday that Kremlin should withdraw the 100,000 troops and equipment deployed on Ukraine’s borders. The US believes that Russia will "invade" the former Soviet Republic soon like what it did in Crimea.

"There will be a swift, severe and united response to any form of aggression by Russia directed to Ukraine,” Blinken told reporters after the Geneva meeting.

Russia on its part wants that the US “shall not establish military bases” in the territories of any former Soviet States that are not already members of the NATO, or “use their infrastructure for any military activities or develop bilateral military cooperation with them.”

Last Wednesday Biden told a press conference, that he expects Putin to order an invasion of Ukraine, and warned that “a disaster” awaits Russia if that happened.

“It is going to be a disaster for Russia if they further invade Ukraine. Our allies and partners are ready to impose a severe cost on Russia and the Russian economy ... And I think he’ll regret having done it (invasion)", Biden said.

Blinken recently met Ukrainian President Volodymyr Zelenskyy and Foreign Minister Dmytro Kuleba in Kyiv. He reaffirmed America’s support and commitment to Ukraine.

Ukrainian officials doubt if the country will get material support from European Union as it is dependent on Russian gas.

As Ukraine has been seeking entry into the NATO, Russian officials told its members and the US last week that it is “absolutely mandatory to make sure that Ukraine never, never, ever becomes a member of NATO.” According to NATO's Constitution, an attack on one member is considered as an attack on all its members.