The 66th Missile Squadron (66 MS) is an inactive United States Air Force unit. It was last assigned to the 44th Operations Group, stationed at Ellsworth AFB, South Dakota.The 66 MS was equipped with the LGM-30F Minuteman II Intercontinental ballistic missile (ICBM), with a mission of nuclear deterrence. With the end of the Cold War, the 66th was inactivated on 1 September 1993.