The Biden administration and the Kremlin have just two weeks to negotiate the extension before the treaty expires on Feb. 6. Complicating the talks, Mr. Biden has said he intends to retaliate against Russia for a sweeping hacking operation last year that breached government and corporate computers in the United States.
Mr. Biden is also expected to take a more forceful position on Russia’s military interventions in Libya, Syria and Ukraine, and on the poisoning and arrest of the country’s most prominent domestic opposition figure, Aleksei A. Navalny.
Mr. Peskov, the Kremlin spokesman, said Russian officials would study the Biden administration’s offer before formally agreeing to an extension. He noted that Ms. Psaki had said the treaty could be extended without new conditions.
“Before now, this wasn’t the conversation,” Mr. Peskov said. “Certain conditions for the extension were put forward, some of which absolutely didn’t suit us. So, let’s first get acquainted with what the Americans are offering,” before responding.
The new moves to extend the treaty coincided with largely symbolic but potentially more profound disarmament news: a United Nations treaty that outlaws nuclear weapons officially took effect Friday, the first time such weapons are banned under international law. Fifty-one countries have ratified the pact, the Treaty on the Prohibition of Nuclear Weapons.
The United States, Russia, and the world’s other nuclear powers — Britain, China, France, India, Israel, North Korea and Pakistan — have rejected the treaty, and many Western leaders have called it naïve and dangerous. Treaty proponents argue that as more countries ratify it, the coercive shaming pressure on the holdout nuclear powers will pressure them to disarm.
Peter Maurer, president of the International Committee of the Red Cross, one of the treaty’s outspoken supporters, said it “sends a clear signal that nuclear weapons are unacceptable from a moral, humanitarian, and now a legal point of view.”
Rick Gladstone contributed reporting from New York.