Russia's President Vladimir Putin on Saturday ordered the start of strategic nuclear exercises involving launches of ballistic missiles, the RIA news agency cited the Kremlin as saying.
The exercises are Moscow's latest show of strength at a time of acute tension with the West over Ukraine.
"Yes," Kremlin spokesperson Dmitry Peskov was quoted as saying when asked if the drills had begun.
Separately, Belarusian President Alexander Lukashenko, a close ally of Putin, took part in military exercises alongside Putin from a situation center in the Kremlin, Belarusian state media reported.
The drills follow a huge series of maneuvers by Russia's armed forces in the past four months that have included a build-up of troops -- estimated by the West to number 150,000 or more -- to the north, east and south of Ukraine. Russia denies planning to attack Ukraine.
Putin and other top officials frequently refer to the fact that Russia, together with the United States, is one of the world's leading nuclear powers.