Tier One (military)

The term Special Mission Unit or Special Missions Unit (SMU) is used to describe some elitespecial operations forces around the world. The term has been applied to the United Kingdoms Special Air Service Regiment and the Australian Defence Force's Special Air Service Regiment and five United States special operations forces units. Special mission units have been involved in high profile military operations such as the death of Osama Bin Laden and capture of Saddam Hussein.

Special mission units are commanded and controlled by Joint Special Operations Command (JSOC) of U.S. Special Operations Command (USSOCOM). In addition to performing highly classified activities the special mission units are also tasked with "special missions", sometimes referring to unconventional warfare, counter-terrorist activities, direct action, Special reconnaissance, and/or black operations. So far, only four SMUs have been publicly disclosed:

- The Army's 1st Special Forces Operational Detachment – Delta.

- The Army's 75th Ranger Regiment: Regimental Reconnaissance Company.

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Wikipedia