The treaty, signed in 2010 by President Barack Obama and Russian President Dmitry Medvedev, limits each country to no more than 1,550 deployed nuclear warheads and 700 deployed missiles and bombers, and envisages sweeping on-site inspections to verify compliance.
Biden indicated during the U.S. presidential campaign that he favored the preservation of New START, which was negotiated during his tenure as vice president under Obama.
Russia had long proposed prolonging the pact without any conditions or changes, but the Trump administration waited until last year to start talks and made the extension contingent on a set of demands. The talks stalled, and months of bargaining failed to narrow differences.
After both Moscow and Washington withdrew from the 1987 Intermediate-Range Nuclear Forces Treaty in 2019, New START is the only remaining nuclear arms control deal between the two countries.
Earlier this month, Russia announced that it would follow the U.S. in pulling out of the Open Skies Treaty, which allowed surveillance flights over military facilities to help build trust and transparency between Russia and the West.