Brunei–Malaysia border which are defined by agreements, from west to east, are as follows: Brunei and Malaysia in an Exchange of Letters on 16 March 2009, agreed to affirm the five agreements. The two countries also agreed to use the watershed principle to determine the remaining undelimited portions of the border. Brunei's maritime boundary with Malaysia until the 100 fathom isobath was inherited from the Sarawak (Definition of Boundaries) Order in Council 1958 No 1518 and the North Borneo (Definition of Boundaries) Order in Council 1958 No 1517, both of which defined the boundary between Brunei on the one hand, and Sarawak
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