The United States exercises global economic, political, and military influence. It is a permanent member of the United Nations Security Council and New York City hosts the United Nations Headquarters. It is a member of the G8, G20, and Organisation for Economic Co-operation and Development. Almost all countries have embassies in Washington, D.C., and many have consulates around the country. Likewise, nearly all nations host American diplomatic missions. However, Cuba, Iran, North Korea,Bhutan, Libya, and the Republic of China (Taiwan) do not have formal diplomatic relations with the United States.
The United States has a "special relationship" with the United Kingdom and strong ties with Canada, Australia, New Zealand, Japan, South Korea, and Israel. It works closely with fellow NATO members on military and security issues and with its neighbors through the Organization of American States and free trade agreements such as the trilateral North American Free Trade Agreement with Canada and Mexico. In 2008, the United States spent a net $25.4 billion on official development assistance, the most in the world. As a share of gross national income (GNI), however, the U.S. contribution of 0.18% ranked last among twenty-two donor states. In contrast, private overseas giving by Americans is relatively generous.
The president holds the title of commander-in-chief of the nation's armed forces and appoints its leaders, the secretary of defense and the Joint Chiefs of Staff. The United States Department of Defense administers the armed forces, including the Army, Navy, Marine Corps, and Air Force. The Coast Guard is run by the Department of Homeland Security in peacetime and the Department of the Navy in time of war. In 2008, the armed forces had 1.4 million personnel on active duty. The Reserves and National Guard brought the total number of troops to 2.3 million. The Department of Defense also employed about 700,000 civilians, not including contractors.
Military service is voluntary, though conscription may occur in wartime through the Selective Service System. American forces can be rapidly deployed by the Air Force's large fleet of transport aircraft, the Navy's eleven active aircraft carriers, and Marine Expeditionary Units at sea with the Navy's Atlantic and Pacific fleets. The military operates 865 bases and facilities abroad, and maintains deployments greater than 100 active duty personnel in 25 foreign countries. The extent of this global military presence has prompted some scholars to describe the United States as maintaining an "empire of bases."
Total U.S. military spending in 2008, more than $600 billion, was over 41% of global military spending and greater than the next fourteen largest national military expenditures combined. The per capita spending of $1,967 was about nine times the world average; at 4% of GDP, the rate was the second-highest among the top fifteen military spenders, after Saudi Arabia. The proposed base Department of Defense budget for 2011, $549 billion, is a 3.4% increase over 2010 and 85% higher than in 2001; an additional $159 billion is proposed for the military campaigns in Iraq and Afghanistan. As of September 2010, the United States is scheduled to have 96,000 troops deployed to Afghanistan, and 50,000 to Iraq. As of January 5, 2011, the United States had suffered 4,432 military fatalities during the Iraq War, and 1,448 during the War in Afghanistan.