A Marine expeditionary unit (MEU, pronounced as one syllable "" IPA: mjuː) is the smallest air-ground task force (MAGTF) in the United States Fleet Marine Force. Each MEU is an expeditionary quick reaction force, deployed and ready for immediate response to any crisis, whether it be natural disaster or combat mission. Marine amphibious unit (MAU) was the name used until the late 1980s.
A MEU normally is composed of
a reinforced USMC infantry battalion (designated as a Battalion Landing Team) as the ground combat element
a composite medium tiltrotor squadron forming the aviation combat element
a combat logistics battalion providing the logistics combat element
a company-size command element serving as the MEU headquarters group.
Troop strength of a MEU is about 2,200 (normal and peacetime) to 4,400 (mobilization and wartime). A MEU is usually commanded by a colonel, and is deployed from amphibious assault ships. Currently, a MEU embarks personnel and equipment on the amphibious warfare ships of an expeditionary strike group (ESG), which also includes escort warships and submarines to protect them from air, surface, and submarine threats. For further protection and strong air support, an ESG is often deployed along with one or more carrier strike groups.
The MEU is unique in that its air and ground combat elements are combined with a logistics combat element under one commander; other services do not unite the command of air and ground forces until much higher command levels.
The MEU's ground combat element also combines artillery, light armor, and tanks at a much lower level than was common in the Army until the development of the brigade combat team early in the War on Terror, with a similar concept, the combat command, being utilized in World War II.
This air-ground task force concept is designed to thoroughly exploit the combat power inherent in air and ground assets by closely integrating them into a single force. The MEU brings all the supplies and logistical support it needs to sustain itself for quick mission accomplishment or to pave the way for any follow-up forces.