ITV News Senior International Correspondent Johnny Irvine reports on what the rare talks between Joe Biden and Vladimir Putin mean amid the growing Ukraine invasion fears
It came after Russia- which is seeking assurances that Ukraine will not join Nato - moved thousands of troops to the border, although it insists it has no intention of attacking its former Soviet neighbour.
Western powers, however, are demanding that Kyiv's sovereignty be respected, with the Americans saying in advance that Putin's request was a non-starter.
Just hours before the call, Ukrainian officials said Russia had escalated the crisis by sending tanks and snipers to war-torn eastern Ukraine to “provoke return fire” and lay a pretext for a potential invasion.
In a brief snippet from the start of the meeting broadcast by Russia state television, the two leaders offered friendly greetings to each other at the start of what was expected to lengthy talk.
“I welcome you, Mr President,” Putin said, speaking with a Russian flag behind him and a video monitor showing Mr Biden in front of him.
“Good to see you again,” Mr Biden replied with a chuckle. He then quickly noted Putin’s absence from the recent G20 summit in Rome.
The Russian leader took part in the major gathering of industrial nations by video link because of concerns about Covid-19 at home.
“Unfortunately, last time we didn’t get to see one another at G20,” Mr Biden said. “I hope next time we meet to do it in person.”
Mr Biden aimed to make clear that his administration stands ready to take actions against the Kremlin that would exact “a very real cost” on the Russian economy, according to White House officials.
“We’ve consulted significantly with our allies and believe we have a path forward that would impose significant and severe harm on the Russian economy,” White House press secretary Jen Psaki said on Monday in previewing the meeting.
“You can call that a threat. You can call that a fact. You can call that preparation. You can call it whatever you want to call it.”
The leader-to-leader conversation - Mr Biden speaking from the Situation Room, Putin from his residence in Sochi - was one of the toughest of Mr Biden’s presidency and comes at a perilous time.
US intelligence officials have determined that Russia has massed 70,000 troops near the Ukraine border and has made preparations for a possible invasion early next year.
Mr Biden was vice president in 2014 when Russian troops marched into the Black Sea peninsula of Crimea and annexed the territory from Ukraine.
Aides say the Crimea episode - one of the darker moments for former president Barack Obama on the international stage - looms large as Mr Biden looks at the current crisis.
Russia has long resisted Ukraine's move towards European institutions, and its central demand has been that it never joins Nato or has Nato infrastructure on its soil.