Biden urged Americans to immediately leave Ukraine as Russia's live-fire drills and build-up of troops around Ukraine deepened fears of an invasion.
Tents and troop housing at the Kursk training area in Russia on February 9.
While en route to meet President Vladimir Putin earlier this week, French President Emmanuel Macron was asked whether "Finlandisation" could be a possible way of averting a Russian invasion of Ukraine.
The term comes from Finland's Cold War stance of being forced into neutrality in return for avoiding a Soviet invasion.
Pictures show troop deployment in Oktyabrskoye airfield in Crimea.
Although Macron did not use the term 'Finlandisation' himself, he said that the policy of neutrality was among "the models on the table" but warned that the situation cannot end up "in a no-man's land, with no possibility of sovereignty or security" for Ukraine.
Nonetheless, the mention of Finlandisation provoked a strong response from many Finnish foreign-policy watchers, for whom the period represents a painful episode in the Nordic nation's history.
This satellite image released by Maxar Technologies shows equipment and new deployments at Novoozernoye in Crimea on February 9.
US President Joe Biden urged Americans Thursday to immediately leave Ukraine, as Russia's live-fire drills and build-up of troops around the ex-Soviet state deepened fears of an invasion.
Washington-Moscow tensions are at their highest since the Cold War, with some US estimates saying some 130,000 Russian soldiers are grouped in dozens of combat brigades near the border with Ukraine.
Satellite image of armoured vehicles deployed at the Zyabrovka airfield in Belarus.
Biden's remarks were released hours after Russia rolled its tanks across Belarus for live-fire drills that drew an ominous warning from NATO and added urgency to Western efforts to avert war on the continent.
NATO said Russia's deployment of missiles, heavy armour and machine-gun toting soldiers marked a "dangerous moment" for Europe some three decades after the Soviet Union's collapse.
This satellite image shows troop housing area and battle group vehicles at park Rechitsa in Belarus.
Western leaders have been shuttling to Moscow in an effort to keep the lines of communication open, giving Russia a chance to air its grievances about NATO's expansion into eastern Europe and ex-Soviet states.
But they have also sought to project their resolve in the face of what they is Russian escalation of an already-tense situation.
"Russia should not underestimate our unity and determination as a partner in the EU and as an ally in NATO," German Chancellor Olaf Scholz warned.
Satellite image of Russian artillery training at Novoozernoye in Crimea.
Russia's defence ministry insisted the exercises would center around "suppressing and repelling external aggression" and the Kremlin has promised the troops will go home after the exercises.
But Ukraine's President Volodymyr Zelensky said "the accumulation of forces at the border is psychological pressure from our neighbours".
Kyiv has launched its own military drills expected to mirror Russia's games, but officials have said little about them out of apparent fear of escalating tensions.
In an icy landscape of birches and pines on NATO's eastern border, this year's regular military exercises by the alliance have come at a time of spiralling tensions between Russia and the West.
The "Winter Camp" exercise in northeast Estonia, just 100 kilometres (62 miles) from the Russian border, included some 1,300 British, Estonian and French troops operating in extreme conditions.
It comes as Russia amasses troops around Ukraine and demands the withdrawal of foreign NATO forces from Poland and the Baltic states of Estonia, Latvia and Lithuania, all EU and NATO members.
The US Air Force announced Thursday a set of B-52 strategic bombers had landed in Britain for scheduled NATO exercises, amid heightened tensions between the bloc and Russia over Ukraine.
The North Dakota-based aircraft, support equipment, and personnel touched down at a Royal Air Force base 150 kilometers (90 miles) west of London, in Fairford, England, the command of US Air Forces in Europe said in a statement.
It did not specify how many US aircraft would be participating in the exercises.
The statement explained that the "long-planned" Bomber Task Force mission aims to improve "cooperation and operational capacity, capability and interoperability" among allies.