This monograph examines the role of pseudo operations in several foreign counterinsurgency campaigns. Pseudo operations are those in which government forces disguised as guerrillas, normally along with guerrilla defectors, operate as teams to infiltrate insurgent areas. This technique has been used by the security forces of several other countries in their operations, and typically it has been very successful. A number of factors must be taken into account before attempting pseudo operations, especially their role in the intelligence and operational systems. Although it is likely that most insurgent movements have become more sophisticated, many of the lessons learned from previous pseudo operations suggest their continued usefulness in counterinsurgency campaigns.