From 1948 to 1991, U.S. foreign and defense policies were dominated by concern about the Soviet Union. During most of this period the United States pursued a policy of containment based on the premise that the Soviet Union was an aggressor nation bent on global conquest. Containment policy led the United States into wars in Korea and Vietnam and led to development of a large defense establishment. U.S. military forces are deployed around the globe, and the nation has a large nuclear arsenal. The end of the cold war, however, has made some of this weaponry and much of the traditional military strategy less relevant to maintaining America's security. Cutbacks in military spending and a redefinition of the military's role are under way.
With the end of the cold war the United States has taken a new approach to foreign affairs, which President George Bush labeled as a "new world order." It proposes that nations work together toward common goals and includes efforts to address global problems, such as drug trafficking and environmental pollution. The Persian Gulf war is the most notable example of the multilateralism that is a characteristic of the new world order.
Increasingly, national security is being defined in economic terms. After World War II, the United States helped establish a global trading system within which it was the leading partner. The nation's international economic position, however, has gradually weakened owing to domestic problems and to the emergence of strong competitors, particularly Japan and Germany. Many analysts believe that a revitalized economic sector rather than military power holds the key to America's future position in international affairs.
The chief instruments of national security policy are diplomacy, military force, economic exchange and intelligence gathering. These are exercised through specialized agencies of the U.S. government, such as the Departments of State and Defense, which are largely responsive to presidential leadership. Increasingly, national security policy has also relied on international organizations, such as the UN and WTO, which are responsive to the global concerns of major nations.