Some 200 Chinese ships have been spotted near the Philippine-occupied Thitu Island in the South China Sea since the start of the year, triggering alarm in the Philippine military.

Philippine soldiers will continue their patrols in the disputed area, military chief Gen. Benjamin Madrigal Jr. said, adding that Chinese fishing vessels have repeatedly been spotted near the island. He urged a panel with representatives from both nations tasked with resolving South China Sea disputes to address Chinese presence in the area.

“This is a concern not only for the military, but for other agencies as well, including the Coast Guard. We are looking for ways to address this,” Madrigal told reporters on the sidelines of opening ceremonies for annual joint military drills between the Philippines and the U.S.

China’s foreign and defense ministries didn’t immediately reply to faxed requests for comment.

Thitu Island, which Manila calls Pag-asa, is part of the disputed Spratly Islands, a series of reefs and shoals in the South China Sea. The area, which lies 480 kilometers (300 miles) west of the Philippines’ Palawan province, is also claimed by Taiwan and Vietnam.

China claims over 80 percent of the sea, through which vast amounts of trade passes — and which is estimated to hold billions of dollars worth of gas reserves.

Manila won an arbitration case in 2016 nullifying Beijing’s claims. But Philippine President Rodrigo Duterte set aside the victory, opting to foster friendlier ties with China, tap Chinese loans for infrastructure projects, and discuss a possible joint oil exploration deal.

More than 7,000 soldiers from the Philippines and the U.S. are participating in this year’s military drills, Madrigal said, which have continued to take place despite Duterte’s 2016 call to split with his biggest military ally. A small delegation from Australia’s armed forces is also joining this year’s military exercises.