On Sunday, United States President Joe Biden assured Ukrainian President Volodymyr Zelensky in a phone call that the US will respond "decisively" if Russia invades.
White House Press Secretary Jen Psaki said in a statement that the leaders expressed support for "diplomatic efforts," adding that Biden made it clear that the United States and its allies will respond firmly if Russia begins a military assault on Ukraine."
The call comes days after Biden spoke with Russian President Vladimir Putin for the second time in a month in response to rising frictions along Russia's border with Ukraine, where Russia has deployed approximately 100,000 soldiers.
Psaki referred to current diplomatic efforts, which include the bilateral Strategic Stability Dialogue between the United States and Russia, as well as negotiations between NATO and Russia and the Organization for Security and Cooperation in Europe.
Additionally, the U.S. official reaffirmed Biden's dedication to Ukraine's sovereignty and territorial integrity.
According to the White House, Biden and Zelenskiy discussed preparations for a series of planned diplomatic sessions to address the problem.
They discussed collaborative steps aimed at preserving Europe's peace and averting further escalation, Zelenskiy wrote on Twitter.
U.S. and Russian representatives are scheduled to meet in Geneva on January 9 to 10, followed by Russia-NATO Council talks and a meeting of the Organization for Security and Cooperation in Europe.
Before those meetings, Biden said he told Putin that it was critical for the Russians to take steps to ease the tensions.
On Sunday, Democratic Rep. Adam Schiff said that economic sanctions against Russia could be the most effective way to deter them from attacking Ukraine, warning that such a move was "very likely."
Last week, Putin warned Biden that U.S. sanctions could lead to a total breakdown of relations between the two countries.
Putin has stated that tens of thousands of troops have been deployed to Russia's border with Ukraine for security reasons, and has warned the West against expanding its alliance by including Ukraine.
Biden has stated that the U.S. is prepared to supply Ukraine with lethal weaponry in the event of a Russian incursion, as well as economic sanctions against Russia.
Russia annexed Crimea from Ukraine in 2014 and is accused of instigating a pro-Russian separatist conflict in Ukraine's east that same year.
Officials from Moscow have said that any future NATO military expansion must exclude Ukraine and other former Soviet republics, as well as a demand that the military alliance remove offensive equipment from the region.
