The UK has started withdrawing diplomats and their families from Ukraine due to fears that Russia could invade.
Half of diplomatic staff and their families stationed at the UK's outpost in Kiev will now leave the country, sources told the BBC.
The move is not due to any specific threat against Britons in the country, the sources said, but is due to the growing risk of a Russian attack.
It comes after the US ordered families of American diplomats out of the country for the same reason, and offered non-essential embassy staff flights home.
The EU said today that it has no plans to withdraw its diplomatic staff from Ukraine, with top diplomat Josep Borrell saying there is no need to 'dramatise' the situation.
Russia has massed 100,000 troops on the Ukrainian border and issued a list of security demands to the US and its NATO allies.
The alliance has described most of the list - including a ban on Ukraine joining and the withdrawal of troops from former Soviet states - as 'non-starters', though high-level talks are ongoing with the US due to provide a written response this week.
America has warned Russia of a 'swift and severe' response if it invades Ukraine, which would include a dramatic escalation of sanctions against the country.
The US is also thought to be considering military options to deter Putin, short of a direct confrontation between Russian and American troops.
Pentagon officials presented one plan to Joe Biden during a summit at the weekend, which would see between 1,000 and 5,000 US troops deployed to Baltic states Lithuania, Estonia and Latvia, which border Russian territory.
Troop numbers could then be increased up to 50,000 if the security situation deteriorates, backed up by fresh deployments of ships and aircraft.
The plan would not involve American troops deployed directly to Ukraine, with Biden thought to be loathe to enter another conflict following his disastrous withdrawal of US troops from Afghanistan last year, the New York Times reports.
Biden could make a call on military measures as soon as this week.
Amid warnings from the Pentagon that an invasion is 'imminent', families of US diplomats stationed in Ukraine were ordered to leave the country.
Non-essential embassy staff were also offered a route out of the country due to 'increased threats of Russian military action'.
But the EU on Monday warned against 'dramatising' the situation and said it has no plans to withdraw its own diplomats.
Josep Borrell, the EU's top diplomat, said he is not aware of any 'specific reasons' to withdraw diplomatic staff and added that negotiations are ongoing.
It comes after the UK alleged at the weekend that Moscow has been making preparations to install a puppet government to take control of Ukraine in the wake of any invasion.
The Foreign Office even went so far as to name former Ukrainian MP Yevhen Murayev as a potential Kremlin candidate.
A senior Biden administration official declined to confirm specific troop numbers on Sunday but said 'we are developing plans and we are consulting with allies to determine options moving forward.'
Defense Secretary Lloyd Austin and Chairman of the Joint Chiefs of Staff Gen. Mark Milley both attended the meetings virtually.
None of the military options being looked at would see the deployment of additional American troops to Ukraine itself with the president keen to avoid entering another conflict.
Biden is expected to make a decision as early as this week but it appears weaponry is already on the move.
Ukraine's Defense Minister Oleksii Reznikov tweeted on Sunday night that the government had received a second shipment of weapons from the United States.
'The second bird in Kyiv! More than 80 tons of weapons to strengthen Ukraine's defense capabilities from our friends in the USA! And this is not the end,' Reznikov tweeted, together with photos of the incendiary cargo.
President Joe Biden and Russian President Vladimir Putin are pictured meeting in June 2021
The briefing saw Defense Secretary Lloyd Austin, left, and Chairman of the Joint Chiefs of Staff Gen. Mark Milley both attending virtually
National security adviser Jake Sullivan and counselor to the President Steve Ricchetti joined Biden in person at Camp David as part of the meetings.
'President Biden was briefed on the current state of Russian military operations on Ukraine's borders and discussed both our ongoing efforts to de-escalate the situation with diplomacy and our range of deterrence measures that are being coordinated closely with our Allies and partners, including ongoing deliveries of security assistance to Ukraine.
'President Biden again affirmed that should Russia further invade Ukraine, the United States will impose swift and severe consequences on Russia with our Allies and partners,' a readout of the briefing said.
The goal military reinforcement in eastern Europe would essentially be to provide deterrence and reassurance to allies.
The options include the 'movement of assets and forces already in Europe and also assets and forces available outside of Europe.'
The Biden administration is also looking at using a 'novel export control' that could damage certain Russian industries, such artificial intelligence, quantum computing and aerospace, if any invasion occurs.
According to the Washington Post, it would involve the U.S. deliberately stopping the flow of components
