MOSCOW • Russia has conducted a final test of a nuclear-capable glider that flies at 20 times the speed of sound, President Vladimir Putin said, adding that the weapon will be added to the country's arsenal next year.

Mr Putin described the successful test, in which the glider was launched from a site in south-western Russia towards a target on the Kamchatka Peninsula more than 5,600km away, as a "wonderful, perfect New Year's gift for the country".

The fanfare surrounding the test - it led the television news, and state media reported that Mr Putin gave the launch order - underscores how central nuclear sabre-rattling has become to the Kremlin's effort to depict Russia as a global superpower for audiences at home and abroad.

The new weapon, dubbed the Avangard, is of a type that the Pentagon has been both working on and worrying about as an arms race emerges among the United States, Russia and China for missiles that can manoeuvre easily and travel far faster than the speed of sound.

There was no immediate, independent confirmation of the test.

After being launched by a rocket, a vehicle carrying a potentially nuclear payload detaches and glides back to earth at hypersonic speeds.

It is so fast and agile, Mr Putin claimed when he unveiled it in a speech in March, that it will be able to evade missile defences for years to come.

"Russia now has a new kind of strategic weapon," Mr Putin told his Cabinet ministers in televised remarks on Wednesday.

The United States is also working on hypersonic missiles, some of them launched from airplanes, although US officials have warned in recent months that the efforts lag behind those of potential adversaries.

Russia has pointed to US missile defences to justify the development of hypersonic boost-glide missiles that can carry nuclear weapons.

Although the US missile defence system is not designed to take on Russia's strategic missiles, with a limited number of installations in California and Alaska and a few interceptors in Europe, Moscow has long been unnerved by the prospect of a system that could undermine its nuclear deterrent.

That is one of the rationales for the super-speedy, nimble Avangard. Traditional intercontinental ballistic missiles travel in a predetermined arc and do not manoeuvre, making them easier to shoot down with missile defence interceptors.