Russia is gearing up to search for a missing nuclear-powered cruise missile that was lost at sea during a failed test-fire last year.
Russian President Vladimir Putin has boasted about the weapon's advanced capabilities, but all tests have reportedly ended in failure.
Sauce
https://www.businessinsider.com/russia-to-search-for-nuclear-powered-cruise-missile-lost-at-sea-2018-8
While the missile is supposed to be able to fly indefinitely, its nuclear-powered core has yet to initiate to allow it to do that.