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–Malaysia border Exchange of Letters were not revealed immediately after the signing on 16 March 2009 and news and information regarding the implementation of the terms the agreement, as well as its impact, has been scarce. However, a Brunei news report on 23 April 2010, more than a year after the signing, quoting the Sultanate's Second Minister for Foreign Affairs and Trade Lim Jock Seng, said Brunei had "retained ownership" of the two petroleum blocks which Malaysia had previously claimed. Lim was also quoted as saying that the matter was "sorted out during last year's agreement". However, as the question to Lim