MANILA (AP) — Chinese and Philippine vessels engaged in a new confrontation in the South China Sea on Friday, with Manila charging that a Chinese coast guard ship and accompanying vessels conducted dangerous maneuvers and blasted a Philippine supply ship with a water cannon in disputed waters.

China responded that it acted appropriately under maritime law to defend what it says is its territory.

The incident was the latest in a series of maritime confrontations between the two nations over territorial disputes that risk turning into more serious armed engagements.

Tensions have risen recently as China has blockaded an isolated Philippine marine outpost on Second Thomas Shoal, also known as Ayungin Shoal.

Last month, a Chinese coast guard ship and an accompanying vessel rammed a Philippine coast guard ship and a military-run supply boat near the contested shoal, according to Philippine officials. China accused the Philippine vessels of trespassing in what it said were Chinese waters “without authorization” despite repeated radio warnings.

A Philippine government task force dealing with the South China Sea said Friday that vessels belonging to China’s coast guard and its paramilitary Maritime Militia “recklessly harassed, blocked and executed dangerous maneuvers in another attempt to illegally impede or obstruct a routine resupply and rotation mission.”

It said a Chinese coast guard ship used a water cannon to blast the Philippine supply vessel M/L Kalayaan, which was en route to deliver supplies to the outpost.

The resupply mission was carried out successfully despite the harassment, it said in a statement.

“We firmly insist that Chinese vessels responsible for these illegal activities leave the vicinity of Ayungin Shoal immediately,” it said, adding that the Philippine Embassy in Beijing delivered a protest to the Chinese Foreign Ministry.

The Chinese coast guard said two small cargo vessels and three Philippine coast guard ships “arbitrarily trespassed into the waters near China’s Ren’ai Reef.” China uses its own names for many locations in the South China Sea.

China’s coast guard “followed the Philippines ships in accordance with the law, taking necessary control measures, and made temporary special arrangements for the Philippines side to transport food and other daily necessities,” coast guard spokesperson Gan Yu said in a statement.

It urged the Philippines to stop actions that infringe upon China’s rights and said China would continue to uphold its national sovereignty.

Territorial conflicts in the South China Sea involving China, the Philippines, Vietnam, Malaysia, Taiwan and Brunei have long been regarded as a potential flashpoint and a delicate fault line in the U.S.-China rivalry.

After last month’s incident in which Chinese ships blocked and collided with two Philippine vessels off the contested shoal, the United States renewed a warning that it would defend the Philippines in case of an armed attack under a 1951 treaty.