The Philippine government is planning to build a new airstrip in Pag-asa Island, one of the disputed islands in the West Philippine Sea (South China Sea).

The development of the island, according to an official of the Department of Foreign Affairs, is “an exercise of Philippine sovereignty, which all countries should respect.”

The Chinese Foreign Ministry earlier called on the Philippines not to complicate the territorial disputes in the region by building infrastructure in the Kalayaan (Spratly or Nansha) Islands.

Hernandez, however, maintained that Pag-asa Island in the Kalayaan Island Group (KIG) is part of the country’s exclusive economic zone.

“[The] Philippines exercises territorial sovereignty, jurisdiction and effective administration in accordance with international law [on Pag-asa Island],” he said.

“The waters and continental shelf around and between the KIG and the Philippine archipelago form part of the national territory of the Philippines,” he added.

There is no formal protest yet from China over the plan to build an airstrip, although its foreign ministry urged the Philippines to follow the 2002 Declaration on the Code of Conduct (DOC).

The DOC, which was signed by China and the member-nations of the Association of Southeast Asian Nations (Asean), prohibits claimant-countries from taking any actions in the region that might complicate the issue.

Part of the prohibition is the building of infrastructure on any of the disputed islands.

Asean groups the Philippines, Singapore, Indonesia, Thailand, Malaysia, Vietnam, Laos, Cambodia, Myanmar and Brunei Darussalam.

Of the 10-member bloc, four countries—the Philippines, Malaysia, Vietnam and Brunei—claimants to the mineral-rich islands.

China and Taiwan also have overlapping territorial claims.

The Chinese foreign ministry said that they will “closely watch the development of the situation.”