Moscow's top arms control official said Tuesday that Russia is prepared for a world without U.S.-Russian nuclear limits after the New START treaty expires this week.

Unless the two sides reach a last-minute understanding, they will be ‌left without any constraints on their long-range strategic nuclear arsenals ‍for the first time in more than half a century when New START expires Thursday.

"This is a new moment, a new reality – we are ready for it," Russian Deputy Foreign Minister Sergei Ryabkov, who oversees arms control issues, told Russian news agencies during a visit to Beijing for "strategic stability consultations."

New START, which caps the number of deployed strategic warheads at 1,550, was signed in 2010.

In comments to the New York Times last month, U.S. President Donald Trump indicated that he will let the treaty expire. But he has not formally responded to a Russian proposal to keep observing the treaty's missile and warhead limits for one ⁠more year to allow time to work out what to do after the pact expires.