The Studies and Observations Group (SOG) was an extremely secret American special force which conducted unconventional warfare operations prior to and during the Vietnam War. The teams consisted of 1-5 Americans and undefined number of Nungs and Yards, tribesmen of Vietnam, Laos, Thailand and Cambodia.

The American team members were drafted from forces like the Navy SEALs and the Green Berets. SOG operated in Vietnam, Cambodia, Laos and Thailand.