JAKARTA - This week’s military exercises near the territorially disputed South China Sea are not provocative, Indonesian Foreign Minister Retno Marsudi said Wednesday, because they are part of routine drills within the country’s maritime territory.

Indonesia’s air force will kick off its largest military exercises Thursday near the Natuna Islands, largely as a show of its sovereignty over the gas-rich area on the fringe of territory claimed by China, officials said.

President Joko Widodo launched an unprecedented campaign to bolster fishing, oil exploration and defense facilities around the Natuna island chain four months ago, after a series of faceoffs between the Indonesian navy and Chinese fishing boats.

China, while not disputing Indonesia’s claims to the Natuna Islands, has angered Indonesia by saying the two countries have overlapping claims to the nearby waters that Indonesia calls the Natuna Sea.

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“I want to emphasize, this is not the first or only military exercise by Indonesia,” the foreign minister said. “We’ve done them several times and the military exercise is in Indonesian territory — not in South China Sea, but in the Natuna Sea, which is part of Indonesia.”

According to a report by IHS Jane's Defence Weekly, the October 6 drill is planned to “simulate an air raid and the seizure of a captured runway ... on Pulau Natuna Besar,” a piece of territory close to the area that Beijing asserts is Chinese.

China’s claims are based on its so-called nine-dash line of sovereignty across the South China Sea, a standard whose legal legitimacy recently was rejected by a U.N.-backed tribunal.

“We want to show our existence in the area, [that] we have a good enough air force to act as a deterrent,” said Air Commander Jemi Trisonjaya, a spokesperson for the Indonesian air force.

About 2,000 military personnel will be involved in Thursday’s exercises, which he said would include deployment of special operations ground forces, transport aircraft, helicopters and Indonesia’s fighter jet, both Russian-made Sukhois and U.S.-made F-16s.

Indonesian legislator Tantowi Yahya, chairman of parliament’s defense commission, told VOA’s Indonesia Service that Jakarta recently allocated $35 million to strengthen a military base in the Natuna Sea.

“Natuna is the farthest and most outer region, [so], in case something happens, it would take time to handle it,” he said. “To strengthen the region, should something unwelcome occur, we need to fortify the area with additional soldiers, facilities and infrastructural development.”

China claims almost the entire South China Sea, where about $5 trillion worth of trade passes every year. Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have claims over islands and waters in the area.

This report was produced in collaboration with VOA's Indonesia Service. Some information is from Reuters.