In 1964 Utah Construction & Mining built an underground control center for Minuteman launching facilities at the Grand Forks Air Force Base in North Dakota. Two years later, the 321st Strategic Missile Wing, the nation's first Minuteman II ICBM wing, arrived and became fully operational in December 1966. Currently, Grand Forks is charged with guarding all 50 states with modified Minuteman missiles designed to intercept enemy missiles before they re-enter the atmosphere. The Minuteman's advantages over the earlier Atlas and Titan series were considerable. Conceived in the late 1950s, the Minuteman series represented the first "push-button" (literally turn-key) missile. This was a solid fuel weapon that could be mass-produced and would not require fueling immediately before being launched. The threat of nuclear war continued to loom as Kennedy's successor, President Lyndon B. Johnson, became preoccupied with a conventional war in Southeast Asia. The rationale for the Vietnam War was the "domino theory" of Communist expansion worldwide. Utah Construction & Mining built an airstrip and facilities in Thailand, used by the United States and its allies. Interestingly, Marriner Eccles was an early and vocal critic of the Vietnam War, believing it to be a drain on the national economy.