Russian President Vladimir Putin has overseen test launches of the country’s most powerful rockets.
Putin reportedly said the exercises simulated a retaliatory nuclear strike.
It comes after Britain said it had deployed a destroyer to track a Russian aircraft carrier sailing close to its coastal waters.
“Today, as part of the planned events, we will activate all the different armed forces of the Russian Federation, over all of the territory of Russia,” explained Putin, adding, “Including the nuclear forces.”
The president also attended a ceremony in Moscow honouring those who lost their lives during World War II.
Next month, Putin will meet Western leaders for the first time since the Ukraine crisis started.
US President Barack Obama and German Chancellor Angela Merkel are amongst the other leaders expected at the ceremony to mark the 70th anniversary of the D-Day landings in Normandy.