Signed in 2010, New START caps at 1,550 the number of nuclear warheads that can be deployed by Moscow and Washington, which control the world's largest nuclear arsenals.
Russian President Vladimir Putin has signed off on legislation extending a key nuclear pact between Russia and the United States by five years.
"Russian President Vladimir Putin signed the federal law 'on the ratification of the extension of the agreement between Russia and the USA'," the Kremlin said in a statement, referring to New START.
"The current federal law enters force on the day of its official publication," the statement said.
The New START treaty is the last remaining arms reduction pact between the former Cold War rivals.
The Kremlin said the extension of the pact "allows to preserve the transparency and predictability of strategic relations between Russia and the United States, [and] to support global strategic stability."
Russia's parliament had backed the extension earlier this week.
A new start
Putin had submitted the bill to both houses of parliament after the Russian leader and new US President Joe Biden held their first phone call Tuesday evening.
Addressing the World Economic Forum being held virtually this year, Putin on Wednesday hailed the extension of the treaty as a positive development in reducing global tensions.
"No doubt it is a step in the right direction," Putin said.
Signed in 2010, New START caps to 1,550 the number of nuclear warheads that can be deployed by Moscow and Washington, which control the world's largest nuclear arsenals.
The agreement, which is due to expire on February 5, is seen as a rare opportunity for compromise between Moscow and Washington, whose ties have dramatically deteriorated in recent years.
Earlier this month, Russia announced that it would follow the US 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.
Arms control advocates hailed New START's extension as a boost to global security and urged Russia and the US to start negotiating follow-up agreements.
Russian Deputy Foreign Minister Sergey Ryabkov, the country's lead negotiator on New START, said earlier this week that Russia was ready to sit down for talks on prospective arms cuts that he indicated should also involve non-nuclear precision weapons with strategic range.
Russia had offered before Biden took office to extend New START for five years – a possibility that was envisaged by the pact at the time it was signed.