Ambalat

Ambalat refers to a disputed maritime area in the Celebes Sea, off the eastern coast of Borneo. The term is associated with the Ambalat offshore block, a region that lies near the coasts of East Kalimantan, Indonesia, and the Malaysian state of Sabah. The area is claimed by both Indonesia and Malaysia as part of their exclusive economic zones (EEZs) and continental shelves, leading to a long-running bilateral dispute over sovereignty and access to natural resources, especially oil and gas.

The core of the dispute is the delimitation of maritime boundaries under international law, including the United Nations Convention on the Law of the Sea (UNCLOS). Indonesia asserts sovereignty over the Ambalat block based on its baselines around Borneo; Malaysia relies on its own baselines and proximity to Sabah. In the 2000s, both governments granted exploration licenses to state-owned or private companies, resulting in periodic confrontations at sea and heightened diplomatic protests. Armed navy patrols and coast guard vessels have been reported in the area during times of tension.

While talks have occurred at various levels, no mutually accepted border agreement has been reached, and the Ambalat issue remains handled through bilateral dialogue and periodic confidence-building measures. The dispute is one of several ongoing maritime boundary disagreements between Indonesia and Malaysia and reflects broader tensions over how UNCLOS boundaries are interpreted and applied in practice.