Special reconnaissance (SR) is conducted by small units, such as a recon team, made up of highly trained military personnel, usually from special forces units and/or military intelligence organizations. Special reconnaissance teams operate behind enemy lines, avoiding direct combat and detection by the enemy. As a role, SR is distinct from commando operations, but both are often carried out by the same units. The SR role frequently includes covert direction of airstrikes and indirect fire, in areas deep behind enemy lines, placement of remotely monitored sensors, and preparations for other special forces. Like other special forces, SR units may also carry out direct action and unconventional warfare, including guerrilla operations.
In intelligence terms, SR is a human intelligence (HUMINT) collection discipline. Its operational control is likely to be inside a compartmented cell of the HUMINT, or possibly the operations, staff functions. Since such personnel are trained for intelligence collection as well as other missions, they will usually maintain clandestine communications to the HUMINT organization and will be systematically prepared for debriefing. They operate significantly farther forward than even the most forward friendly scouting and surveillance units.
In international law, SR is not regarded as espionage if combatants are in proper uniforms, regardless of formation, according to the Hague Convention of 1907, or the Fourth Geneva Convention of 1949. However, some countries do not honor these legal protections, as was the case with the Nazi "Commando Order" of World War II, which was held to be illegal at the Nuremberg Trials.
While SR has been a function of armies since ancient times, specialized units with this task date from the lead-up to World War II.
In 1938, the British Secret Intelligence Service (MI6) and the War Office both set up special research departments: Section D and "Military Intelligence (Research)" to investigate possible sabotage and other ways to attack the enemy.