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
Indonesia–Malaysia confrontation an abject failure, the poorly trained and equipped forces were unable to seize key objectives such as capturing the Sultan of Brunei, seize the Brunei oil fields, or take European hostages. Within hours of the insurrection being launched, British forces based in Singapore were being mobilised for a prompt response. The failure of the insurrection was clear within 30 hours when Gurkha troops airlifted from Singapore secured Brunei town and ensured the Sultan's safety. The degree of Indonesian support for the TNKU remains a subject of debate. While Indonesia at the time denied direct involvement, it did sympathise with the