By Tom Balmforth
MOSCOW (Reuters) - Russia said on Friday there was no longer enough time left for Moscow and Washington to negotiate a full-fledged replacement for the New START nuclear arms control treaty before it expires in February 2021.
The New START accord is the last major nuclear arms control treaty between the world's two biggest nuclear powers and limits the number of strategic nuclear warheads they can deploy.
The fate of the accord has been in the spotlight since Washington in August pulled out of another landmark strategic arms accord, the Intermediate-Range Nuclear Forces Treaty (INF), citing violations by Russia that Moscow denies.
"It's already obvious that with the time that is left... we will not be able to work out a full-fledged replacement document," Vladimir Leontyev, a foreign ministry official, was quoted as saying by Interfax news agency.
The treaty can be extended by mutual agreement, but the prospect of that happening is unclear as Washington is not moving quickly and Moscow would need at least half a year to implement any extension agreement, Leontyev said.
There was no immediate reaction from Washington to his comments.
Leontyev said talks between the United States and Russia had been complicated by Washington proposing that China be made a party to a new accord.
The INF treaty was negotiated by then-U.S. President Ronald Reagan and Soviet leader Mikhail Gorbachev. It banned land-based missiles with a range of between 310 and 3,400 miles (500-5,500 km), reducing the ability of both countries to launch a nuclear strike on short notice.
The demise of the INF treaty put strains on the global arms control architecture erected during the Cold War to prevent an arms race between Washington and Moscow. Last year President Vladimir Putin announced an array of new-generation nuclear-powered missiles.
Leontyev said three of those weapons systems, including the Poseidon underwater nuclear drone and the Burevestnik nuclear-powered cruise missile, did not fall under the new START treaty.
U.S. officials have said President Donald Trump will decide only next year whether or not to extend the New START treaty.
The existing accord was signed by Trump's predecessor, Barack Obama, in 2010. It also curbs the number of nuclear launchers and deployed land- and submarine-based missiles and nuclear-capable bombers they can have.
(Reporting by Tom Balmforth; additional reporting by Andrei Kuzmin; Editing by Timothy Heritage)