After the activation of the 509th Composite Group in December 1944, some members of the group (including members of the 393rd Bombardment Squadron, the unit's combat squad) went to Cuba for training. At Batista Field in San Antonio de Los Baños, the group trained for a month. They worked on long-range, over-water flights, in preparation for the long haul between Tinian Island and Japan. The avoided formation flights so crews would adjust to flying solo. The same airfield would appear again in nuclear history, when it was used as a staging ground for Soviet planes during the Cuban Missile Crisis.