Russia’s Defense Ministry announced Tuesday the start of three-day strategic nuclear exercises focused on preparing the armed forces to respond to external threats.

The May 19-21 drills, involving 64,000 military personnel and 7,800 pieces of equipment, will include the launch of ballistic and cruise missiles and take place across regions in the Leningrad and Central military districts.

Hundreds of missile launchers, as well as aircraft, ships and submarines, will also take part in the exercises, the Defense Ministry said, adding that Russia’s Northern and Pacific fleets would be involved.

In a statement, the military said the main objective of the exercise is to practice the preparation and deployment of its nuclear forces under a simulated “threat of aggression.”

The drill announcement comes a day after the Belarusian Defense Ministry said it launched its own nuclear weapons exercises in coordination with the Russian military.