This document is Field Manual 3-39.40, which provides guidance for commanders and staffs on internment and resettlement operations. It addresses internment and resettlement across the spectrum of conflict, from major combat operations to humanitarian assistance missions. It describes the doctrinal foundation, principles, and processes that military police and other elements will employ when dealing with internment and resettlement populations such as detainees, U.S. military prisoners, and dislocated civilians. Military police conduct internment and resettlement operations during various types of operations and provide support to detainee operations and confinement of U.S. military prisoners.