Russian President Vladimir Putin watched on Thursday as the country's armed forces tested missiles that can carry thermo-nuclear warheads.
The Grom-19 or Thunder-19 strategy games began on Wednesday and involve 12 000 troops deployed on ships, planes and nuclear-missile-carrying submarines carrying out launches of long-range precision missiles, the defence ministry said.
The games, which do not involve foreign forces, come soon after Russia and the US abandoned their 1987 Intermediate Nuclear Forces treaty, which limited the use of nuclear and conventional medium-range weapons.
The drills were used to test RS-24, RSM-50 and Sineva intercontinental ballistic missile systems, the ministry said. They employed more than 200 launchers.
Putin visited the national defence control centre in Moscow to watch a video transmission of the live launches, accompanied by defence minister Sergei Shoigu, Russian television showed.
Shoigu said the armed forces were simulating "tasks in an armed conflict and nuclear war", deploying "highly accurate nuclear weapons and weapons based on new physical principles".
The defence ministry said cruise and ballistic missiles were fired from the Barents Sea and the Sea of Okhotsk by submarines of the northern and Pacific fleets. They landed at the Kura missile test site in far eastern Kamchatka and the Chizha test site in northwestern Russia.
The ministry had said earlier that the scenario involved heightened tensions on Russia's border that threatened its sovereignty, while adding that the scenario was purely defensive in nature.