Russia tested a new nuclear-capable and powered cruise missile fit to confound existing defences, inching closer to deploying it to its military, President Vladimir Putin said.
The announcement, which followed years of tests of the Burevestnik missile, comes as part of nuclear messaging from the Kremlin, which has resisted Western pressure for a ceasefire in Ukraine and strongly warned the US and other NATO allies against sanctioning strikes deep inside Russia with longer-range Western weapons.
A video released on Sunday by the Kremlin showed Putin, dressed in camouflage fatigues, receiving a report from General Valery Gerasimov, Russia's chief of general staff, who told the Russian leader that the Burevestnik covered 14,000 kilometres in a key test last Tuesday.
Gerasimov said the Burevestnik, or storm petrel in Russian, spent 15 hours in the air on nuclear power, adding"that's not the limit".
Little is known about the Burevestnik, which was code-named Skyfall by NATO, and many Western experts have been sceptical about it, noting that a nuclear engine could be highly unreliable.
When Putin first revealed that Russia was working on the weapon in his 2018 state-of-the-nation address, he claimed it would have an unlimited range, allowing it to circle the globe undetected by missile defence systems.
Many observers argue such a missile could be difficult to handle and pose an environmental threat.
The US and the Soviet Union worked on nuclear-powered missiles during the Cold War, but they eventually shelved the projects, considering them too hazardous.
The Burevestnik reportedly suffered an explosion in August 2019 during tests at a navy range on the White Sea, killing five nuclear engineers and two service members and resulting in a brief spike in radioactivity that fuelled fears in a nearby city.
Russian officials never identified the weapon involved, but the US said it was the Burevestnik.
"We need to determine the possible uses and begin preparing the infrastructure for deploying these weapons to our armed forces," Putin told Gerasimov.
The Russian leader also claimed it was invulnerable to current and future missile defences, due to its almost unlimited range and unpredictable flight path.
Last week, Putin directed drills of Russia's strategic nuclear forces that featured practice missile launches. The exercise came as his planned summit on Ukraine with US President Donald Trump was put on hold.
