On August 8, during testing aboard a barge in the White Sea near Nyonoksa, Russia, the nuclear engine of an experimental nuclear-armed cruise missile exploded, killing two technicians and injuring six others. On August 11, officials of the Russian nuclear agency Rosatom acknowledged that five employees had died in the explosion of what they described as "an isotopic power source for a liquid engine installation." The head of the nuclear research center, Valentin Kostyukov, called the five "national heroes."
As of today, it is believed that the death toll has risen to seven. The victims were described as suffering from burns, and most were thrown into the sea by the explosion; they all likely suffered from radiation burns.
The nuclear-powered cruise-missile program was announced by Russian Federation President Vladimir Putin on March 1, 2018, during an address to the Federal Assembly. Putin described the weapon as a nuclear-powered, nuclear-armed cruise missile with essentially unlimited range, intended to defeat any ballistic missile defenses deployed by the United States.