Malaysia and Indonesia are currently embroiled in an amicable dispute over land boundaries in the Sumatra and Kalimantan islands of Indonesia, where the two countries have long shared a land border as neighbours. The land boundary between what is now Indonesia and Malaysia itself can be traced back to colonial arrangements made by the Dutch and British, via a treaty penned in 1915, The Independent SG reports. The treaty mentioned parts of Borneo, with Sebatik Island divided between the two countries. However, the fact that the legal foundations of the land remain rooted in agreements drawn during colonial rule, it leaves certain issues poorly defined given that both nations have now gained independence.
Despite clear legal references, there was no conclusive decision applicable to every segment of the border on the ground. Ever since 1977, both countries have embarked on joint technical committees that worked through what are officially called “Outstanding Boundary Problems” (OBPs). The unresolved areas are mostly located near rivers, where natural shifts happen, causing a complication in demarcation because of incomplete mapping.
As of now, there are still nine of such zones that remain unsettled, four along the Sarawak–West Kalimantan border and five between Sabah and North Kalimantan. Malaysian Prime Minister Anwar just last week stressed that these locations cannot be claimed by either side until negotiations conclude. In stating this, the prime minister further emphasises that border determination is still ongoing and incremental rather than finalised.
The persistent flashpoint that is Ambalat
Beyond land negotiations, maritime tensions between the two have been continuous, centred on the Ambalat Block that spans the Sulawesi Sea, Tempo.co reports. The dispute can also be traced back to other unclear colonial maritime boundaries, which later diverged interpretations of international law. Indonesia grounds its claim in UNCLOS principles, asserting rights as an archipelagic state. Malaysia, on the other hand, holds onto a unilateral maritime map issued in 1979 and its proximity to Sipadan and Ligitan.
Throughout the 1980s and 1990s, both countries increased patrols and went through multiple diplomatic protests as resource exploration in the area intensified. Tensions reached a high point back in 2009, when Malaysia signalled plans to explore for oil and gas in the area, which prompted Indonesia to bolster its naval presence. Despite repeated talks, Ambalat remains unresolved, though both sides have consistently rejected military escalation.
In 2025, the talks over Ambalat once again resurfaced thanks to the clashes along the Thailand and Cambodia border. As such, there was a concern that Malaysia and Indonesia might follow the same approach, though PM Anwar publicly stated that this is not the case. Anwar confirmed that he had raised the issue directly with Indonesian President Prabowo Subianto, confirming that discussions would continue under international law, including UNCLOS.
The Nunukan villages
Early in 2026, public attention reverted back to the three villages in Indonesia’s Nunukan regency: Kabungalor, Lipaga and Tetagas, Antara News reports. Indonesian officials had stated that these villages were now recorded as falling within Malaysian territory following agreements reached at a bilateral meeting in February 2025. They added that Indonesia would, in turn, receive 5,207 hectares of land for border infrastructure and a planned free-trade zone.
These remarks triggered widespread concern on Indonesian social media, with claims circulating that the territory had been abruptly “lost.” Indonesian authorities moved quickly to calm public anxiety, stressing that the boundary process had unfolded over many years and that no sudden changes had taken place.
But Anwar, responding to the uproar, addressed Malaysia’s Parliament in a special briefing to reject allegations that Kuala Lumpur had agreed to hand over land to Indonesia, The Independent SG reports. He described reports suggesting a 5,200-hectare transfer as false and misleading.
According to Anwar, border disputes should not be settled through compensation or land swaps. Instead, every metre is negotiated strictly within existing legal frameworks. He urged lawmakers not to politicise the issue, warning that distorted narratives risk undermining long-standing bilateral relations and public trust.
Indonesia opts for a review
On the Indonesian side, State Secretary Prasetyo Hadi said the government would conduct direct field inspections in the Nunukan area to gain a clearer understanding of conditions on the ground. He emphasised that any steps to be taken would involve coordination across ministries and agencies, with no rushed decisions.
Local border officials echoed this stance, denying claims that villages had been “lost” due to border changes. They clarified that recent parliamentary meetings focused on accelerating development and improving welfare in border communities, not redrawing lines. The message was consistent: the process is ongoing, methodical, and far from complete.
With all these issues unfolding, the Malaysia–Indonesia border dispute persists not because of sudden political manoeuvres, but because it sits at the intersection of colonial legacies, international law, resource competition, and domestic politics. Each flare-up reveals how easily technical negotiations can be overwhelmed by public narratives, especially in the age of social media.
While both governments continue to anchor their positions in law and diplomacy, the real challenge lies in managing perception. Public opinion can easily become a digital kangaroo court that can sway and narrate the next moves albeit prematurely. Without clearer public communication, unresolved borders risk becoming political symbols rather than legal questions, prolonging disputes that neither side truly wants to escalate.
