Indonesia–Malaysia confrontation of the action occurring in the border area between Indonesia and East Malaysia on the island of Borneo (known as Kalimantan in Indonesia). The conflict was characterised by restrained and isolated ground combat, set within tactics of low-level brinkmanship. Combat was usually conducted by company- or platoon-sized operations on either side of the border. Indonesia's campaign of infiltrations into Borneo sought to exploit the ethnic and religious diversity in Sabah and Sarawak compared to that of Malaya and Singapore, with the intent of unraveling the proposed state of Malaysia. The challenging jungle terrain of Borneo and lack of roads straddling
Brunei revolt form Malaysia, Indonesia became actively involved in subterfuge operations and later declared war on Malaysia. During this period, Indonesian agents came into contact with local opposition that was against the idea of a federation. The rebellion broke out at 2:00 am on 8 December. Signals from Brunei to British Far East Headquarters reported rebel attacks on police stations, the Sultan’s Istana, the Prime Minister’s house and the power station, and that another rebel force was approaching the capital by water. Far East Headquarters ordered ALE YELLOW, which placed a force of two Gurkha infantry companies on 48 hours notice to