Jakarta. President Prabowo Subianto has formally resolved a long-standing territorial dispute between the provinces of Aceh and North Sumatra, ruling that four contested islands near oil and gas-rich waters belong to Aceh.

The decision, announced by State Secretary Prasetyo Hadi after a limited cabinet meeting led by the president on Tuesday, ends nearly a century of administrative uncertainty.

“The government, based on documentation and supporting data, has determined that Lipan Island, Panjang Island, Mangkir Gadang Island, and Mangkir Ketek Island are administratively part of the Aceh province,” said Prasetyo.

The verdict follows an extensive review involving the Home Affairs Ministry, provincial documents, and spatial data from several government agencies. The islands had previously been designated under North Sumatra’s jurisdiction based on a 2025 ministerial decree, sparking opposition from Aceh authorities who cited historical claims.

Aceh Governor Muzakir Manaf praised the decision and President Prabowo’s leadership in settling the issue. “We hope the matter is now fully resolved, with no party disadvantaged. The most important thing is that the islands remain within the Republic of Indonesia,” Manaf said during a joint press conference at the State Palace in Jakarta, attended by North Sumatra Governor Bobby Nasution and several cabinet members via video call.

The four islands lie near the Offshore West Aceh (OSWA) oil and gas block, a strategic area currently operated by Conrad Asia Energy Ltd. The block, along with the adjacent Offshore North West Aceh (ONWA), is believed to hold vast energy resources. OSWA spans 8,200 square kilometers and has estimated gas reserves of 296 billion cubic feet (BCF), while ONWA is believed to contain up to 192 million barrels of oil and 1.1 trillion cubic feet (TCF) of gas.

While oil and gas reserves directly beneath the four islands remain unconfirmed, their proximity to major exploration blocks heightened the stakes in the dispute.

Despite their proximity to North Sumatra’s coast, Aceh has long claimed historical control over the islands, a position backed by colonial-era maps dating back to 1928. However, the islands were omitted from Aceh’s list of 260 verified islands in a 2008 national mapping initiative, while North Sumatra included them in its count.

Subsequent spatial analysis by the Home Affairs Ministry in 2017 supported North Sumatra’s claim, but Aceh contested the findings, citing outdated coordinates. The dispute escalated again in 2020 when a ministerial decision reaffirmed the islands’ placement under North Sumatra, prompting Aceh to demand a new survey.

A factual survey in 2022 revealed that while the islands are uninhabited, they contain cultural and religious markers such as graves and monuments erected by the Aceh government. Pulau Lipan was noted as being partially submerged.

Following further review of historical and factual evidence, Jakarta formally ruled in favor of Aceh in 2025, effectively concluding a dispute that had spanned nearly 100 years.