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
Foreign relations of Brunei as close military relations with the latter island-state. Aside from relations with other ASEAN states, of which the Philippines, Indonesia, and Malaysia are key partners, Brunei also has extensive relations with the Islamic and Arab world outside its region. Brunei became a member state of the United Kingdom Commonwealth in 1984, ASEAN, the United Nations and the Organisation of Islamic Cooperation) in 1984, the Organisation of Islamic Cooperation, a major player in BIMP-EAGA in 1994., a founding member of the World Trade Organization (WTO) in 1995, Since 2009 Brunei and the Philippines signed a memorandum of understanding (MOU) that seeks