Indonesia, explained.
History, law and politics continue to intersect uncomfortably (Getty Images)
A border row between Malaysia and Indonesia is reviving memories of older unresolved territorial fights.
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Sabah’s borders: Indonesia joins Malaysia-Philippines disputeSabah’s borders: Indonesia joins Malaysia-Philippines dispute
The recent controversy over Malaysia’s border negotiations with Indonesia along the Sabah-Kalimantan frontier has a familiar echo to those who know Sabah’s history. Malaysian Prime Minister Anwar Ibrahim told parliament on 4 February that Malaysia denied ceding 5,207 hectares to Indonesia, insisting the border demarcation followed agreements dating back to 1891 and 1915.
Territorial disputes over Sabah are nothing new as the Philippines have laid claim to the territory for decades. Philippine President Ferdinand Marcos Jr recently acknowledged that the issue was “briefly mentioned” during his 2023 state visit to Malaysia, though both sides agreed to focus on “solvable” issues rather than their territorial differences.
The Philippines enacted the Maritime Zones Act and Archipelagic Sea Lanes Act in November 2024, prompting Malaysia to lodge a formal protest in February 2026. Kuala Lumpur objected that the legislation’s definition of Philippine maritime zones and sea lanes encroached on Malaysia’s maritime zones north of Sabah.
The dispute originated from historical claims made by the Philippines over Sabah, which has been part of Malaysia since 1963. The Philippine claim dates back centuries, to when the Sultan of Sulu – whose domain covered parts of the southern Philippines – once ruled there. In the 19th century, the territory was owned by a succession of private commercial companies until it became a British Protectorate in 1888 and was administered by the British North Borneo Company. After the Second World War, North Borneo – as Sabah was then known – became a British Crown Colony on 15 July 1946. From the British perspective, the ownership of North Borneo was not in doubt as the territory had become a crown colony through the North Borneo Cession Order in Council.
The contemporary dispute rests on the debate over whether the Sultan “ceded” or “leased” the land to the British North Borneo Company in 1878. Manila first formally lodged its claim in June 1962, just as Britain prepared to unite its Borneo colonies with Malaya to form the Federation of Malaysia. The dispute was then overshadowed by Confrontation (Konfrontasi) in 1963, when Indonesia launched a diplomatic and military campaign against the new Federation of Malaysia. The Philippines also opposed the union, refusing to recognise the new federation without assurances that the Sabah claim would be negotiated.
What makes the current situation significant is that Indonesia’s border negotiations, like the Philippine claim, reveal how Sabah’s territorial status remains contested.
The Bangkok Accord of 1 June 1966, which ended Confrontation, called for Jakarta to recognise Malaysia’s boundaries and for Kuala Lumpur to give Sabah and Sarawak an opportunity to decide through elections whether to remain in Malaysia. Sabah’s support for continued membership was re-affirmed in April 1967 elections. All 35 Legislative Assembly seats were won by pro-Malaysia parties. Observer teams from Indonesia, Japan, India, Ceylon (now Sri Lanka) and Thailand confirmed the elections were conducted fairly, although the Philippines declined to send observers.
Yet just a few months before the formation of the Association of Southeast Asian Nations (ASEAN) – of which Malaysia, Indonesia and the Philippines were founding members – the British Embassy in Kuala Lumpur reported claims that the Philippines was actively encouraging secessionist sentiment within Sabah’s local government. The matter was not completely dropped after ASEAN’s inauguration, as the Philippines sought a Malaysian agreement to refer the claim to the International Court of Justice.
Bilateral talks proved disastrous. Diplomatic relations were suspended in October 1968 when Manila passed legislation referring to Sabah as Philippine territory. Indonesia and Thailand, concerned about regional cooperation, tried unsuccessfully to bring the parties together.
Malaysia tried to draw Britain, Australia and New Zealand into stronger defence commitments by calling the situation a Philippine threat to the region. At Washington’s suggestion, the Commonwealth allies tried to persuade the Malaysians to stop their activities in the southern Philippines. The Americans were opposed to the Philippine claim but did not want to take part themselves because they wanted to avoid a direct showdown with Manila.
At the second ASEAN Ministerial Meeting in Jakarta on 6–7 August 1968, while representatives of the member states expressed support for regional cooperation, the Sabah dispute continued to simmer behind the scenes. Hopes were pinned on ASEAN members playing a role in restraining the dispute. However, the Indonesians did not want to be drawn into the Sabah dispute, even as mediators, and insisted it be kept off the agenda at the meeting. The British Embassy in Jakarta believed this position was not just because Indonesia was hosting the ministerial meeting, but also because the Philippines held a dormant claim to an adjacent area of Indonesian Kalimantan.
At the end of 1969, Marcos Sr. decided to put the matter aside without formally renouncing the claim and sought to normalise relations with Malaysia. Contributing to this decision was the absence of Sabah as an issue in the November 1969 presidential elections, which Marcos won convincingly.
What makes the current situation significant is that Indonesia’s border negotiations, like the Philippine claim, reveal how Sabah’s territorial status remains contested. There has been no formal dispute over the Sabah-Kalimantan border since 1915, yet decades later survey teams are still confirming boundary markers – part of what Anwar explained as the 47-year negotiation process over border demarcation.
These latest developments highlight the enduring problems relating to colonial-era boundary agreements and the tensions between historical claims and legal frameworks. Sabah’s borders remain contested terrain where history, law and politics continue to intersect uncomfortably.
About the author
Sue Thompson
Dr Sue Thompson is Associate Professor at the National Security College, Australian National University.
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