Summary: The dissolution of the Soviet Union has touched off a national debate over future defense spending levels. Both congressional leaders and the incoming administration have proposed cuts in defense outlays that could result in a smaller military than the Base Force--the level of preparedness that the Pentagon describes as necessary to protect U.S. interests in the post-Cold War era. Although conventional force levels in the current Base Force were originally formulated before the breakup of the Soviet Union, the Pentagon believes that they still fully reflect the current international security situation. The Defense Department's (DOD) force structure decision makes several assumptions about national interests, threats, contingency requirements, military doctrine, and risk. At the heart of the Base Force concept is the ability to deter and defend against uncertain threats in regions critical to U.S. interests, including Europe, Southwest Asia, and the Pacific. Given the relative absence of immediate military threats to U.S. interests, it is unclear how the United States should compare itself militarily to other major nations. GAO cites five key policy issues that policymakers must consider in determining the size and composition of U.S. military forces. These issues provide a framework for debating force structure issues in the future.