Summary: With decreases in defense spending since the end of the Cold War, U.S. defense companies have been looking for sales abroad and the Pentagon has been trying to increase cooperative programs with its major European allies. At the same time, partly in response to their own reduced defense budgets, many European nations have sought to develop a common armament policy and consolidate their defense industrial base to become more efficient and competitive in world markets. This report reviews the changes that have taken place in the European defense market during the past five years and discusses their implications for future U.S. military procurement options. GAO examines (1) the steps that European governments and industry have taken to unify the European defense market, (2) how key European countries' defense procurement practices have affected U.S. defense companies' ability to compete on major weapon competitions in Europe, and (3) how the U.S. government and industry have adapted their policies or practices to the changing European defense situation. GAO focuses on the buying practices of five European countries: France, Germany, Italy, the Netherlands, and the United Kingdom.