The United States began a 24/7 flight program to ensure prompt and reliable retaliation in the event of a sudden Soviet attack. Twelve B-52s armed with H-bombs were kept constantly in the air under all circumstances as part of Operation Chrome Dome. Every day, six B-52s headed north and circumnavigated Canada, four crossed the Atlantic and circled the Mediterranean, and two circled over the Thule base in Greenland. Known as Thule Monitor, it required pilots to maintain constant visual contact with the base, as it was considered the first target the Soviets would hit in the event of conflict. The physical existence of Thule would serve as proof to the Americans that World War III had not yet broken out. Furthermore, half the B-52s were kept on ground alert, loaded with bombs and with the pilots sleeping alongside the aircraft, already on the runway.
