On 26 October 1962, at Malmstrom AFB, MT, the first operational-ready Minuteman I missile went on "strategic alert" after it was discovered the Soviet Union had placed nuclear missiles in Cuba. Over the next four days, the 10th Strategic Missile Squadron placed four more missiles on alert, with the last missile from Alpha-flight achieving alert status 10 November. The Soviets eventually removed their missiles from Cuba. Later, President Kennedy said the Soviets backed down because they knew he had an “Ace in the Hole,” referring directly to the Minuteman missiles of the l0th SMS. In November 1960, the USS George Washington (SSBN-598) became the first ballistic missile submarine to enter service with 16 Polaris A-1 missiles. Between 1960-1966, forty more submarines entered service.