Putin on Sunday oversaw a test of another advanced nuclear-capable weapon -- the Burevestnik cruise missile, which he said had an "unlimited range". Trump called that exercise not "appropriate".

"Yesterday, another test was conducted for another prospective system -- the unmanned underwater device 'Poseidon,' also equipped with a nuclear power unit," Putin said in televised remarks while visiting a military hospital treating Russian soldiers wounded in Ukraine.

The Russian leader said there was "no way to intercept" the drone torpedo, which, according to Putin, can travel at a speed higher than conventional submarines and reach any continent in the world.

Putin said no country could match Poseidon's speed and diving depth, adding, "it is unlikely that anything similar will appear in the near future."

The device can operate at a depth of more than one kilometre (0.6 mile) and travel at speeds of up to 70 knots while remaining undetectable, according to a source in the Russian military-industrial complex quoted by state news agency TASS.

First tested in 2018, it is capable of carrying a nuclear warhead of up to two megatons, the source told TASS.

After Sunday's cruise missile test, Trump urged Putin to focus instead on ending the war in Ukraine.

"He ought to get the war (in Ukraine) ended. A war that should have taken one week is now soon in its fourth year. That's what he ought to do instead of testing missiles," Trump said.

The US president last week scrapped a planned summit with Putin in Budapest over what he cast as the Russian leader's unwillingness to compromise to end the conflict.

Trump has been trying to secure a deal since he returned to the White House in January, but talks have yielded no progress and he has shown increasing frustration with Putin, who has rejected multiple calls for a ceasefire.

Washington last week slapped sanctions on Russia's two largest oil companies, complaining that his talks with Putin to end the Ukraine war "don't go anywhere."

Putin first announced Russia had developed the Burevestnik and the Poseidon during a fiery anti-Western speech in 2018.