Serey Sam, President of KEPO – www.kepo.info
Serey Sam, Phnom Penh
The recent controversy surrounding Malaysia’s border negotiations with Indonesia along the Sabah-Kalimantan frontier carries a familiar ring for those familiar with Sabah’s complex history. On 4 February, Malaysian Prime Minister Anwar Ibrahim told parliament that Malaysia had not ceded 5,207 hectares to Indonesia, stressing that the demarcation followed long-standing agreements from 1891 and 1915. The pragmatic path taken by Philippine President Ferdinand Marcos Sr more than five decades ago—setting the Sabah claim aside without formal renunciation in order to rebuild ties with Malaysia—may hold useful lessons for other regional flashpoints, including China and Taiwan’s maritime disputes with the Philippines and Cambodia’s border tensions with Thailand.
Territorial questions over Sabah are far from new. The Philippines has maintained a claim to the territory for decades. Philippine President Ferdinand Marcos Jr recently noted that the matter was “briefly mentioned” during his 2023 state visit to Malaysia, with both sides choosing to concentrate on practical, solvable issues rather than their territorial differences.
Tensions flared again after the Philippines passed the Maritime Zones Act and Archipelagic Sea Lanes Act in November 2024. Malaysia lodged a formal protest in February 2026, arguing that the laws’ definition of Philippine maritime zones and sea lanes encroached on Malaysian waters north of Sabah.
The dispute traces back to historical claims rooted in the era when the Sultan of Sulu held sway over parts of what is now Sabah. In the 19th century the territory passed through the hands of private commercial companies before becoming a British protectorate in 1888 under the British North Borneo Company. After the Second World War it was made a British Crown Colony on 15 July 1946. From the British viewpoint, ownership was settled by the North Borneo Cession Order in Council.
At the heart of the modern disagreement is whether the 1878 agreement with the British North Borneo Company constituted a cession or a lease. Manila formally advanced its claim in June 1962 as Britain prepared to federate its Borneo territories with Malaya. The issue was soon overshadowed by Indonesia’s Confrontation campaign against the new Federation of Malaysia in 1963. The Philippines also withheld recognition of the federation pending negotiations on the Sabah claim.
The Bangkok Accord of 1 June 1966 that ended Confrontation required Indonesia to recognise Malaysia’s boundaries and gave Sabah and Sarawak the chance to reaffirm their place in Malaysia through elections. Sabah’s voters did so decisively in April 1967, when pro-Malaysia parties swept all 35 Legislative Assembly seats. Observer teams from several countries confirmed the polls were fair; the Philippines declined to send observers.
Even as ASEAN was being formed, with Malaysia, Indonesia and the Philippines among its founders, British diplomats reported that Manila was encouraging secessionist sentiment in Sabah. The Philippines later pressed for the claim to be referred to the International Court of Justice. Bilateral talks collapsed, and diplomatic relations were severed in October 1968 after Manila enacted legislation treating Sabah as Philippine territory. Indonesia and Thailand tried unsuccessfully to mediate, while Malaysia sought stronger defence backing from Britain, Australia and New Zealand. The United States, though opposed to the Philippine claim, preferred to stay clear of a direct confrontation with Manila.
At the second ASEAN Ministerial Meeting in Jakarta in August 1968 the dispute simmered quietly in the background. Indonesia refused to act as mediator and insisted the issue stay off the formal agenda, partly because of its own residual sensitivities over adjacent territory in Kalimantan.
By the end of 1969, President Ferdinand Marcos Sr chose a different path. He decided to set the Sabah claim aside without formally abandoning it and moved to normalise relations with Malaysia. The issue had played little role in the November 1969 presidential election, which he won convincingly. That pragmatic decision allowed bilateral ties to improve and helped stabilise the young ASEAN grouping.
Today’s border talks between Malaysia and Indonesia, and the renewed friction over maritime zones with the Philippines, show that Sabah’s territorial status remains sensitive more than half a century later. There has been no formal dispute over the Sabah-Kalimantan land border since 1915, yet survey teams continue to verify markers as part of a demarcation process that Anwar described as spanning 47 years.
These episodes underline the lasting complications of colonial-era boundaries and the friction between historical assertions and contemporary legal frameworks. In an era of overlapping claims and maritime legislation, the approach taken by Marcos Sr—setting the most intractable differences to one side in order to build cooperative relations—offers a practical template. Prioritising manageable issues and regional stability over maximalist claims may still be the most effective way to manage border and maritime disputes in the present day, whether in the South China Sea involving Taiwan and the Philippines or along the contested frontier between Cambodia and Thailand.
