JAKARTA, Indonesia — Indonesian maritime patrols have successfully intercepted a Chinese coast guard vessel that approached a survey ship in a contested section of the South China Sea for the second time within a week, as reported by local authorities on Thursday.

According to Indonesia’s Maritime Security Agency, the Chinese vessel made two attempts to reach the MV Geo Coral, disrupting a seismic data survey being carried out by the state-run energy firm PT Pertamina. This operation is located in a section of the sea that both countries assert claims over.

The region marked by China’s “nine-dash line” overlaps with Indonesia’s exclusive economic zone extending from the Natuna Islands. A ruling by an international tribunal in 2016 dismissed the majority of China’s expansive territorial claims in the South China Sea. Despite this, China has refused to acknowledge the ruling, labeling it a farce.

Chinese vessels have frequently entered areas that Indonesia refers to as the North Natuna Sea, aggravating the ongoing tensions between the two nations.