Military missions should be based on the nation's military objectives; in turn, force structure mix and size should be derived from the mission roster. One example of the trouble a disconnection of the planning process has caused U.S. defense planners has been the case of strategic bombing. U.S. strategic bombing in World War II did not achieve the objectives that airpower enthusiasts prophesied. After 1945, some felt that the atomic bomb would solve some of the problems experienced in World War II. However, evidence suggests that atomic attack on the USSR probably would have been insufficient to knock the Soviet Union out of a major war. Unfortunately, nuclear airpower came to be the core of the West's defense posture; very powerful thermonuclear weapons seemed to solve technical problems with A-bombing and endorsed continuing fracture in planning. Problems caused by the disconnection of the goals of bombing with traditional national military aims continue to plague U.S. defense planning and foreign policy.