The United States Army Special Forces, also known as the Green Berets because of their distinctive service headgear, are a special operations force. Although the Green Beret rank originated in Great Britain, the Americans have adopted it and many mistakenly refer to the Special Forces as the "Green Berets".
The Special Forces are mainly tasked with five primary missions: unconventional warfare (the original and most important mission of Special Forces), foreign internal defense, special reconnaissance, direct action, and counter-terrorism. The first two emphasize language, cultural, and training skills in working with foreign troops. Other duties include combat search and rescue (CSAR), counter-narcotics, counter-proliferation, hostage rescue, humanitarian assistance, humanitarian demining, information operations, peacekeeping, psychological operations, security assistance, and manhunts; other components of the United States Special Operations Command (USSOCOM) or other U.S. government activities may also specialize in these secondary areas. Many of their operational techniques are classified, but some nonfiction works and doctrinal manuals are available.
As a special operations unit, Special Forces are not necessarily under the command authority of the ground commanders in those countries. Instead, while in theater, SF soldiers may report directly to United States Central Command, USSOCOM, or other command authorities. The Central Intelligence Agency's (CIA) highly secretive Special Activities Division (SAD) and more specifically its elite Special Operations Group (SOG) recruits from the Army's Special Forces. Joint CIA-Army Special Forces operations go back to the famed MACV-SOG during the Vietnam War. This cooperation still exists today and is seen in the War in Afghanistan.