US President Joe Biden and Russian President Vladimir Putin have spoken for about two hours over a secure video call in what had been expected to be a highly consequential meeting for the two leaders amid escalating tensions between Russia and Ukraine.
During the last several months, Russia has erected supply lines, including medical units and fuel, that could sustain a drawn-out conflict should Moscow choose to invade Ukraine, two sources familiar with the latest intelligence assessments told CNN.
And recent US intelligence findings estimate Russia could begin a military offensive in Ukraine in a matter of months as it amasses up to 175,000 troops along the border.
The meeting on Tuesday (US time) lasted about two hours, according to the White House.
In what was expected to be one of the most pivotal foreign policy meetings of Mr Biden's still-young presidency, the President was expected to lay out to Mr Putin what sanctions and other actions the US could take if the Russian President decides to invade Ukraine.
The US intelligence community believes Mr Putin has still not made up his mind to launch a military offensive against Ukraine, and Mr Biden had planned to tell Mr Putin the US is prepared to take "substantive economic countermeasures" meant to inflict "significant and severe economic harm on the Russian economy" should Mr Putin go ahead with a military escalation, a senior administration official told reporters.
On Monday, the Pentagon confirmed that it has continued to observe "added military capability" by Russian forces along the country's border with Ukraine.
Ukraine minister warns of 'massacre'
The meeting was held as Ukrainian Defence Minister Oleksiy Reznikov has told CNN there will be a "really bloody massacre" if Russia decides to invade Ukraine, and warned that "Russian guys also will come back in the coffins," amid heightened alarm about troop movements on the nations' border.
Mr Reznikov urged Mr Biden to stand firm against Moscow.
"If I can advise President Biden, I would like him to articulate to Mr Putin that no red lines from the Kremlin side should be here. The red line is here in Ukraine and the civilised world will react without hesitation," Mr Reznikov said on Monday (US time).
"The idea of not provoking Russia will not work," he added.
Mr Reznikov that Ukraine assesses that Russia currently has 95,000 troops within striking distance of Ukraine.