Field manual (FM) 3-39.40 is aligned with FM 3-39, the military police keystone FM. FM 3-39.40 provides guidance for commanders and staffs on internment and resettlement (I/R) operations. This manual addresses I/R operations across the spectrum of conflict, specifically the doctrinal paradigm shift from traditional enemy prisoner of war (EPW) operations to the broader and more inclusive requirements of detainee operations. Additionally, FM 3-39.40 discusses the critical issue of detainee rehabilitation. It describes the doctrinal foundation, principles, and processes that military police and other elements will employ when dealing with I/R populations. As part of internment, these populations include U.S. military prisoners, and multiple categories of detainees (civilian internees CIs], retained personnel RP], and enemy combatants), while resettlement operations are focused on multiple categories of dislocated civilians (DCs).