The Indonesian Army (Tentara Nasional Indonesia Angkatan Darat (TNI-AD), Indonesian National Military-Land Force) is the land branch of the Indonesian National Armed Forces. It has an estimated strength of 300,000 active personnel. The history of the Indonesian Army has its roots in 1945 when the Tentara Keamanan Rakyat (TKR) "People's Security Forces" first emerged as a paramilitary and police corps.
Since the nation's independence movement, the Indonesian Army has been involved in multifaceted operations ranging from the incorporation of Western New Guinea, the Indonesia-Malaysia Confrontation, to the annexation of East Timor, as well as internal counter-insurgency operations in Aceh, Maluku, and Papua. The army's operations have not been without controversy; it has been periodically associated with human rights violations, particularly in West Papua, East Timor and Aceh.
The Indonesia Army is composed of a headquarters, 15 military regional command (Kodam), a strategic reserve command (Kostrad), a special forces command (Kopassus), and various adjunct units. It is headed by the Chief of Staff of the Army (Kepala Staf Angkatan Darat – KSAD or KASAD).
In the week following the Japanese surrender of 1945, the Giyūgun (PETA) and Heiho groups were disbanded by the Japanese. Most PETA and Heiho members did not yet know about the declaration of independence. Command structures and membership vital for a national army were consequently dismantled. Thus, rather than being formed from a trained, armed, and organised army, the Republican armed forces began to grow in September from usually younger, less trained groups under the national People's Security Agency built around charismatic leaders in the regions. Creating a rational military structure that was obedient to central authority from such disorganisation, was one of the major problems of the revolution, a problem that remains through to contemporary times.