Malaysia–Philippines border

The Malaysia–Philippines border is a maritime boundary located in the South China, Sulu and Celebes Seas. It separates the Malaysian state of Sabah, which is on the island of Borneo, and the Sulu Islands of the southern Philippines.

The boundary is the result of the division of the Sulu Sultanate through the cession of its territories to colonial powers. The British gained control of the northeast shores of Borneo, which became known as North Borneo and subsequently Sabah, while the rest of the Sulu Islands fell under Spanish control and later United States rule. The Philippines still officially claim the eastern part of Sabah as part of its territory, arguing the validity of the cession by the heirs of the Sultan of Sulu.

This historical backdrop laid the groundwork for a long-standing territorial dispute, reignited through the high-profile Malaysia–Sulu arbitration case. The self-proclaimed descendants of the last Sultan of Sulu filed a multi-billion-dollar claim against the Malaysian government, citing a colonial-era 1878 agreement that granted a British company rights over territory now part of present-day Sabah. Malaysia honored the agreement for decades, paying an annual cession of approximately $1,000 to the Sultan’s heirs until 2013, when it ceased payments following the Lahad Datu standoff. In response, the claimants pursued international arbitration, demanding US$32 billion. In January 2022, Spanish arbitrator Gonzalo Stampa ruled in their favor, awarding US$15 billion, the largest arbitration award in history. However, on 27 June 2023, The Hague Court of Appeal struck down the award, marking a “landmark victory” for Malaysia. Most recently, Stampa was convicted of contempt of court for “knowingly disobeying rulings and orders from the Madrid High Court of Justice,” and sentenced to six months in prison.

Malaysia and the Philippines are also parties to the multinational claims over the Spratly Islands and both countries have overlapping claims over some islands of the archipelago. The historical connections of the people living on both sides of the border has resulted in the border being extremely porous, with a lot of illegal immigration from the Philippines to Malaysia occurring. The porous border has also resulted in several incidents of cross-border raids and kidnapping by armed groups from the Philippines on Malaysian towns and resorts on the east coast of Sabah.