U.S. President Joe Biden and his Russian counterpart Vladimir Putin on Thursday issued warnings to each other amid a standoff over Russia's military buildup on the border with Ukraine, but affirmed diplomatic engagements involving their countries next month.
During the phone call, which was the second exchange between the two leaders in December, Biden reiterated his call for a de-escalation of tensions and made clear that the United States and its allies will "respond decisively" if Russia further invades Ukraine, White House Press Secretary Jen Psaki said in a statement.
Putin warned Biden that "a total severance" of bilateral ties should be expected if the United States moves ahead with "unprecedented sanctions," Russia's Tass news agency reported, citing remarks by Kremlin aide Yuri Ushakov.
The Biden administration has been cautioning that the costs Moscow could suffer in the event of a military escalation toward Ukraine would be "far beyond what was implemented in 2014" following Russia's annexation of Crimea from Ukraine.
The measures are to include economic sanctions, adjustments of the North Atlantic Treaty Organization's force posture in allied countries and additional assistance to Ukraine to enable it to further defend its territory.
Russia has been complaining about what it views as NATO's increasing military activities near the country's border and stepping up its demand for "security guarantees" that would preclude NATO's expansion to Ukraine, among other issues.
The 50-minute phone call between Biden and Putin took place at the request of Russia, according to the White House.
While warning of the possible consequences of a Russian invasion of Ukraine, the Biden administration has been expressing its readiness to engage diplomatically through multiple channels in an apparent bid to seek ways to ease tensions.
The two countries are expecting to hold bilateral talks on nuclear arms control on Jan. 9-10 in Geneva. The event will be followed by a meeting between NATO and Russian representatives and another one between Russia and the Organization for Security and Cooperation in Europe, of which the United States is a member.
A senior Biden administration official said the leaders "agreed to the sequence" of the exchanges ahead and "discussed the importance of pragmatic, results-oriented diplomacy."
"Both leaders acknowledged that there were likely to be areas where we could make meaningful progress as well as areas where agreements may be impossible, and that the upcoming talks would determine more precisely the contours of each of those categories," the official said.
Earlier in December, the Russian government released a draft of a treaty proposal with the United States that would block NATO's eastward expansion, deny accession to the alliance to former Soviet Union republics and rule out military cooperation with such countries.
NATO has said it supports the right of all countries to decide their own future and foreign policy free from outside interference. The United States has also said NATO's door will remain open to those who aspire to membership and who can meet the criteria.