Russia’s Defense Ministry has for the first time released the number of Soviet casualties during the Cuban Missile Crisis.

On Sept. 9, 1962, 55 years before the Defense Ministry published its report, the Soviet Union transferred its first ballistic missiles to Cuba as part of the secret operation “Anadyr.”

The operation came in response to American ballistic missile deployment in Italy and Turkey, as well as the failed Bay of Pigs invasion by U.S. forces.

Sixty-four Soviet citizens died on Cuban territory during the period between the years 1962 and 1964, according to new official data released by the ministry.

This is the first time an exact number of Soviet deaths during the Cuban Missile Crisis period has been provided by an official source. The Defense Ministry did not specify how many of the deaths were soldiers.