MEU's are the smallest air-ground task forces (MAGTF) used by the US Marines, capable of conducting amphibious operations to respond to crises, conduct limited contingency operations, introduce follow-on forces, and support designated special operations forces.
The task forces are characterised by their sea-based forward presence, as well as their expeditionary nature, ability to plan for and respond to crises, combined arms integration, and their interoperability with joint, combined and special operations forces.
There are seven standing MEUs that routinely deploy in accordance with the Global Force Management Implementation Guidance (GFMIG), the 11th, 13th and 15th from the west coast of the US, and the 22d, 24th, and 26th MEUs from the east coast.
The 31st MEU is forward assigned and located in Okinawa, Japan.
The US military defines MEU characteristics as the following:
- Most agile, standing MAGTF;
- Expeditionary by nature;
- Sea-based, strategic reach with inherent force protection;
- Scalable levels of presence and visibility;
- Offers wide range of options for the national leadership;
- Rapid response: within six hours of notification;
- Self-sustaining: 15 days of organic, sea-based logistics;
- Task organised to operate across the range of military operations (ROMO);
- Enables follow-on, joint, interagency and coalition forces;
- Combined arms integration of credible combat power;
- Operates from over-the-horizon and out-of-sight;
- Operates independent of facilities ashore; and
- Capable of integrating with special operations forces.
An MEU is usually composed of a reinforced Marine infantry battalion with a ground combat element, a composited medium tiltrotor squadron (which forms the aviation combat element), a combat logistics battalion providing the logistics combat element, and a company-size command element that serves as the headquarters for the MEU group.
With around 2,200 personnel, the MEU is usually commanded by a colonel, and deployed from amphibious assault ships.