Biden warns Putin of 'swift and severe costs' if Russia invades Ukraine

In a phone call with President Vladimir Putin, President Joe Biden made clear that if Russia invades Ukraine, the US and its allies would respond “decisively and impose swift and severe costs".

According to a readout of the hourlong call, Biden told Putin on Saturday that an invasion would “produce widespread human suffering and diminish Russia’s standing.” 

The US remains committed to diplomacy, but was “equally prepared for other scenarios,” according to the White House.

READ MORE: US withdraws nearly all remaining troops from Ukraine

The two presidents spoke the day after Biden's national security adviser, Jake Sullivan, warned that US intelligence shows that a Russian invasion could begin within days and before the Winter Olympics in Beijing end February 20.

The Biden administration has been warning for weeks that Russia could invade Ukraine soon, but US officials had previously said the Kremlin would likely wait until after the Games ended so as not to antagonize China.

Sullivan told reporters on Friday that US intelligence gleaned show that Russia could take military action the during the Olympics.

Russia has more than 100,000 Russian troops massed near Ukraine’s borders but denies that it intends to launch an offensive against Ukraine.

Russia denies that it intends to launch an offensive against Ukraine.

'United trans-Atlantic response'

US Secretary of State Antony Blinken said he told his Russian counterpart on Saturday that “further Russian aggression would be met with a resolute, massive and united trans-Atlantic response.”

Meanwhile, Ukrainian President Volodymyr Zelenskyy tried to project calm as he observed military exercises Saturday near Crimea, the peninsula that Russia annexed from Ukraine in 2014.

"We are not afraid, we're without panic, all is under control,” he said.

US Defense Secretary Lloyd Austin and his Russian counterpart, Sergei Shoigu, also held telephone discussions on Saturday.

UK troops that have been training the Ukrainian army also planned to leave the country. Germany, the Netherlands and Italy called on their citizens to leave as soon as possible.

A State Department travel advisory on Saturday said most American staff at the Kyiv embassy have been ordered to leave and other US citizens should depart the country as well.

Several NATO allies, including Britain, Canada, Norway and Denmark, also asked their citizens to leave Ukraine, as did non-NATO ally New Zealand.

Adding to the sense of crisis, the Pentagon ordered an additional 3,000 US troops to Poland to reassure allies.

READ MORE: US intensifies diplomatic phone calls amid fears of Russian Ukraine attack