"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 told journalists aboard Air Force One.

Putin on Sunday announced the successful final test of the Burevestnik missile, which he said has "unlimited range".

Trump had promised to quickly end the Ukraine war upon his return to the White House in January, but talks between Moscow and Kyiv have stalled despite the US president's mediation efforts.

Russia's forces are slowly but steadily gaining ground in Ukraine, grinding through Kyiv's defences in costly battles.