 The Soviets suspected the United States of performing a surprise nuclear attack with the Pershing II system, despite the fact that the Pershing II missiles were not delivered to Europe until November 22, eleven days after the conclusion of Able Archer 83.The Soviets believed the United States had determined that a nuclear war was technically winnable.The reason behind this rationale by the Soviet Union was related to the fact that the United States had just recently upgraded its Minuteman III ICBM to the Minuteman IIIA.