GAO provided information on policy considerations, future requirements, and force structure of carrier battle groups, focusing on: (1) the size and makeup of future naval carrier forces in response to reduced defense spending; and (2) alternatives for meeting national security requirements with fewer carriers. GAO found that: (1) changes in the international security environment shifted the U.S. strategy from containment of the former Soviet Union to ensuring regional stability by strategic deterrence, maintaining an overseas presence, crisis response, and maintaining a rebuilding capability; (2) the Navy plans to downsize its battle carrier force to 12 ships even though carrier battle groups are still needed because of their superior sustainability and flexibility capabilities; (3) the costs of procuring new carrier-based aircraft could exceed $120 billion and reduce the affordability of future carrier procurements and the number of aircraft deployed; (4) the Navy plans to extend the life of existing tactical and support aircraft; (5) carrier battle group alternatives, which are intended to fill gaps resulting from downsizing, include utilizing amphibious assault ships and surface combatants equipped with advanced missiles and weapons systems; (6) existing surface combatants could sufficiently fulfill regional contingencies and have strike, antiair, antisurface, and antisubmarine warfare capabilities; (7) advanced assault ships include flight decks, a variety of munitions, and landing craft launch capabilities, but lack multimission capabilities; (8) decreasing the frequency and duration of carrier operations and training will not significantly reduce operation and support costs, since up to 80 percent of the costs are fixed, including maintenance and personnel; and (9) cost savings can be realized by reducing the size of the carrier force and the complement of aircraft.