Presidents Joe Biden and Vladimir Putin have spoken about the Russian troop build-up near Ukraine during their second call in recent weeks.
Mr Putin’s foreign affairs adviser said Mr Biden reaffirmed the US threat of new sanctions against Russia in case of an escalation or invasion, to which Mr Putin responded with a warning that such a move could lead to a complete rupture of ties.
“It would be a colossal mistake that would entail grave consequences,” said Yuri Ushakov. He added that Mr Putin told Mr Biden that Russia would act as the US would if offensive weapons were deployed near American borders.
Ahead of the 50-minute conversation on Thursday, the White House indicated that Mr Biden would make clear to Mr Putin that a diplomatic path remains open even as the Russians have moved an estimated 100,000 troops towards Ukraine and Mr Putin has stepped up his demands for security guarantees in Eastern Europe.
But Mr Biden would reiterate to Mr Putin that for there to be “real progress” in talks they must be conducted in “a context of de-escalation rather than escalation”, according to a senior administration official.
The call, which was requested by Russian officials, comes as senior US and Russian officials are to hold talks on January 10 in Geneva.
Kremlin spokesman Dmitry Peskov said Mr Biden and Mr Putin, who met in Geneva in June to discuss an array of tensions in the US-Russia relationship, were not expected to take part in the coming talks.
The two leaders held a video call earlier this month in which their conversation focused heavily on Russia’s troop movements that have unsettled Ukraine and other European allies.
In that video call on December 7, the White House said Mr Biden put Moscow on notice that an invasion of Ukraine would bring sanctions and enormous harm to the Russian economy. Russian officials have dismissed the sanction threats.
Moscow and Nato representatives are expected to meet shortly after the upcoming Geneva talks, as are Russia and the Organisation for Security and Co-operation in Europe, which includes the United States.
Earlier this month, Moscow submitted draft security documents demanding that Nato deny membership to Ukraine and other former Soviet countries and roll back its military deployments in Central and Eastern Europe.
The US and its allies have refused to offer Russia the kind of guarantees on Ukraine that Mr Putin wants, citing Nato’s principle that membership is open to any qualifying country. They agreed, however, to hold talks with Russia to discuss its concerns.
As Mr Biden prepared for talks with Mr Putin, the administration also sought to highlight the commitment to Ukraine and drive home that Washington is committed to the “principle of nothing about you without you” in shaping policy that affects European allies.
US secretary of state Antony Blinken spoke on Wednesday with Ukrainian President Volodymyr Zelenskyy.
State Department spokesman Ned Price said Mr Blinken “reiterated the United States’ unwavering support for Ukraine’s independence, sovereignty, and territorial integrity in the face of Russia’s military build-up on Ukraine’s borders”.
Mr Biden and administration officials also plan to consult with European allies after the president speaks to Mr Putin.
Mr Putin said earlier this week he would weigh up a range of options if the West fails to meet his push for security guarantees precluding Nato’s expansion to Ukraine.
In 2014, Russian troops marched into the Black Sea peninsula of Crimea and seized the territory from Ukraine. Russia’s annexation of Crimea — one of the darker moments for president Barack Obama on the international stage — looms large as Mr Biden looks to contain the current crisis.
