Operational Detachment Alpha's (ODAs) are the base unit of United States Army Special Forces, the Green Berets. A detachment, also known as a an "A-Team or Team, is comprised of twelve soldiers, each specializing in a specific area that supports the mission of the Green Berets. While the 75th Ranger Regiment (both drawing lineage from the Office of Strategic Services), is considered by some the oldest special operations unit in the army, Special Forces are the oldest continuously active SOF unit in the Army

im

Within Special Forces Groups, ODAs are assigned specializations and receive additional training:

• Military Free-Fall (MFF) Teams: Trained in high-altitude, low-opening parachute operations.American Special Operations
• Combat Diver Teams: Skilled in underwater infiltration and exfiltration techniques.
• Mountain Teams: Experts in alpine warfare and cold-weather operations.
• Mobility Teams: Proficient in operating Ground Mobility Vehicles (GMVs) for rapid movement.American Special Operations

The concept of small, highly specialized units dates back to the World War II-era Office of Strategic Services (OSS), whose operations behind enemy lines laid the groundwork for modern Special Forces. The U.S. Army Special Forces was officially activated in 1952 at Fort Bragg, North Carolina. The ODA concept, modeled in part on OSS "Jedburgh" teams and other Allied irregular units, was developed to be small, flexible, and capable of autonomous operations in denied environments.

In the 1960s and 1970s, ODAs became known for their roles in the Vietnam War, where they conducted long-range reconnaissance and trained indigenous Montagnard forces. Their organizational structure and mission set have evolved since then, but the core principle of working with and through partner forces remains central.

ODAs consist of 12 members, each with a unique military occupational specialty (MOS). 6 ODAs make up a full Special Forces Company.^[1] SF companies usually contain one Operational Detachment Bravo (ODB), of around 12 men, which provides support and command and control to the SF Company's ODAs. ODBs support the training, intelligence and counterintelligence efforts of ODAs

• Detachment Commander (Captain): The Commander is the team leader and is responsible for outfitting his ODA, organizing missions and briefing the unit on mission objectives.
• Assistant Detachment Commander (Warrant Officer 1 or Chief Warrant Officer 2): Colloquially known as the ODA's "Chief", the Assistant Detachment Commander assists the ODA's Commander, ready to take over command if needed. If the ODA splits into two teams, as happened in Gulf War I, then the Chief commands the second team.

• Operations Sergeant (Master Sergeant): The Operations Sergeant is responsible for the overall organization, functionality and training of an SF team. He makes sure the team is outfitted correctly and supports the ODA commander (18A).
• Assistant Operations and Intelligence Sergeant (Sergeant First Class) This team member ensures that the team has all the equipment and supplies needed for the mission. He also gathers and analyzes mission-critical intelligence.
• Weapons Sergeants (Sergeant First Class / Sergeant) Weapons Sergeants are experts in a wide range of U.S. and foreign weapons systems, from pistols and to light artillery and anti-aircraft missiles
• Communications Sergeants (Sergeant First Class / Sergeant) SF Communications Sergeants are proficient in the gamut of radio communications equipment and techniques used in the field, everything from morse code to encrypted satellite transmissions and IT technology.
• Medical Sergeants (Sergeant First Class / Sergeant) Special Forces Medics are first-class battlefield trauma medical technicians as well as being proficient in more general medical care. The ability of SF medics to treat the medical problems of local populations is a valuable component of counter insurgency 'hearts and minds' operations.
• Engineering Sergeants (Sergeant First Class / Sergeant) Engineering Sergeants are the guys you go to when you want something built or destroyed. They are experts in explosive demolitions and can blow bridges, buildings and other structures to kingdom come. SF Engineers are also proficient in military and civil construction and can carry out a range of projects from fortifications to civil engineering tasks such as digging wells or building a schoolhouse.

• ODA 595 (5th Special Forces Group) - aka the "Horse Soldiers", one of the first U.S. military units deployed to Afghanistan after the 9/11 attacks. Their mission involved operating in the mountainous terrain of Northern Afghanistan, working with the Northern Alliance to disrupt and dismantle Taliban operations. Known for using horses during the United States invasion of Afghanistan.^[2]
• ODA 574 (Third Battalion, 5th Special Forces Group) - Known for working with Hamid Karzai during the United States invasion of Afghanistan to help defeat the Taliban and create conditions for the establishment of a democratic government in Afghanistan.
• Detachment A - Based in West Berlin during the Cold War. Officially designated as the 39th Special Forces Detachment (Airborne), it operated from 1956 until its inactivation in 1984. Detachment A was tasked with operations behind enemy lines in the event of a conflict with the Soviet Bloc, including sabotage of key targets and organizing stay-behind resistance in East Germany. Its existence and activities remained highly classified throughout its service.

MARSOC - Marine Raider Team - Small Marine Raider teams are organized to conduct foreign internal defense, training/advising, and direct action alongside partner forces. They overlap strongly with SF ODAs in FID/advising mission sets and expeditionary posture.

Navy SEAL - Platoon / SEAL Team Element - SEAL platoons are small, highly capable tactical units that perform direct action and special reconnaissance. They differ from ODAs in emphasis (maritime/sea-borne and direct action), but at the team level the size, tempo, and tactical employment are comparable.

Special Air Service (SAS) - (squadron / troop level) - SAS troops/squadrons operate in small, autonomous teams for deep reconnaissance, direct action, and training/liaison with partner forces. The SAS tradition of long-range penetration and working through local partners makes it one of the closest equivalents.

Special Boat Service (SBS) - The SBS is the maritime counterpart to the SAS. SBS troops carry out small-team operations in coastal and maritime environments and also conduct training/advising and reconnaissance — comparable in structure and mission flexibility.

Special Air Service Regiment (SASR) - Australia’s SASR uses small patrols for long-range reconnaissance, unconventional warfare and adviser roles in the region. Their small-team focus and regional partner-training missions resemble SF ODA duties.

Canadian Special Operations Regiment (CSOR) / JTF2 - (team elements) - CSOR teams (and JTF2 elements) operate in small detachments for direct action, special reconnaissance, and partner training. CSOR’s emphasis on partner capacity building is especially ODA-like; JTF2 has a stronger CT role but shares the small-team operational model.

• Special operations
• Military organization