New START, the last nuclear treaty between Washington and Moscow after decades of agreements dating to the Cold War, is set to expire on Thursday, and with it restrictions on the two top nuclear powers.

"In just a few days, the world will be in a more dangerous position than it has ever been before," spokesman Dmitry Peskov told journalists, including from AFP, during a daily briefing.

The Kremlin, which has offered a one-year extension of the treaty, said "we still haven't received a response from the Americans to this initiative."

If the treaty is not extended, the world's top two nuclear powers would "be left without a fundamental document that would limit and control these arsenals," for the first time.

US President Donald Trump, who cut many international agreements limiting the United States, said in September that an extension of the New START "sounds like a good idea," but little has changed since then.

The treaty, which included a monitoring mechanism, was signed in 2010 by then-Russian President Dmitry Medvedev and his US counterpart Barack Obama.

But Russia suspended monitoring inspections during the COVID-19 pandemic and talks on extending the agreement have broken down in recent years due to tensions over the Ukraine war.

Moscow had also accused Washington of impeding monitoring missions on US soil.

In 2023, Russia froze its participation in New START, but it has continued to voluntarily adhere to the limits set in the treaty.

Moscow has last year tested its latest nuclear weapon carriers without atomic warheads, and Trump said he was moving two nuclear submarines closer to Russia.