The Philippine defense chief said he asked the visiting U.S. Pacific commander on Wednesday to help protect the transport of fresh Filipino troops and supplies to Philippine-occupied reefs in the disputed South China Sea by deploying American patrol planes to discourage Chinese moves to block the resupply missions.

The Philippines has protested past attempts by Chinese coast guard ships to block smaller boats transporting fresh military personnel, food and other supplies to a Filipino military ship outpost at the disputed Second Thomas Shoal, which is also being claimed and guarded by Chinese coast guard ships. The tense standoff at the shoal has lasted two years.

Defense Secretary Voltaire Gazmin said the commander, Adm. Harry Harris Jr., assured him of U.S. readiness to provide assistance, adding that the U.S. military has flown an aircraft at least once when a Philippine boat delivered supplies last year to Filipino marines marooned on a rusty naval ship that ran aground years ago at the disputed shoal.

AP journalists witnessing a resupply mission last year saw a U.S. military plane hovering above a Filipino supply boat, which a Chinese coast guard ship tried but failed to block.

Such U.S. military flights deter Chinese moves, Gazmin said, adding that Philippine resupply boats have been harassed less by Chinese coast guard ships after the deployment of the U.S. patrol plane.

“If there are Americans flying around there, we won’t be troubled,” Gazmin told The Associated Press in an interview. “We need to be helped in our resupply missions. The best way they could assist is through their presence.”

Second Thomas Shoal, which is called Ayungin by Filipinos and Ren’ai by the Chinese, and the nearby Spratly Islands lie about 120 miles (190 kilometers) from the western Philippine province of Palawan, and about 700 miles (more than 1,000 kilometers) from southern China. China’s foreign ministry says Beijing has “indisputable sovereignty” over the shoal.

The Philippine navy deliberately ran one of its ships aground at the shoal in 1999, fearing that Chinese forces would occupy it after taking control of nearby Mischief Reef four years earlier. A Chinese frigate and maritime surveillance ships arrived in 2013 and the uneasy standoff remains unresolved.

The underfunded Philippine military has turned to the U.S., a longtime treaty ally, to rapidly acquire refurbished warships and planes as the territorial rifts intensified in recent years. Gazmin said Washington has agreed to provide two C-130 cargo planes previously used by the U.S. Marines. The aircraft may be delivered to the Philippine air force next year.

Harris indicated the U.S. may be able to provide a third U.S. Coast Guard cutter in addition to two earlier ones, which have become the largest frigates of the Philippine navy.

The U.S. has a policy of not taking sides in the territorial disputes but has declared it has a national interest in ensuring freedom of navigation and overflight in the South China Sea, one of the world’s busiest shipping lanes. The long-seething territorial rifts involving China, the Philippines and four other governments have sparked fears of those freedoms being hampered in waters, where a bulk of the world’s oil and trade passes. (AP)