The head of the Philippine military said on Monday he was with his forces aboard a supply boat when it was blasted with a water cannon and barged by Chinese coastguard ships over the weekend in the disputed South China Sea.

China, meanwhile, accused the United States of encouraging the Philippines, its treaty ally, to provoke China for its own purposes, though it provided no direct evidence.

The successive days of heated confrontations underscore China’s determination to assert its claim to virtually the entire South China Sea, despite the possibility of fomenting a larger conflict affecting shipping and other maritime activities in the crucial waterway.

General Romeo Brawner Jr told the Associated Press that China was escalating its aggression in the contested waters but said it would not deter Filipino forces from defending their territorial interests.

More than 100 official Chinese and other government-linked ships have swarmed the high seas around the contested Second Thomas Shoal, where a marooned Philippine navy ship that Brawner visited has stood for decades. He said their presence was much bigger than in previous months.

“It’s pure aggression,” Gen Brawner said. “I witnessed how many times the big Chinese coastguard and militia ships cut our path. They water-cannoned us, then bumped us. It’s angering.

“This really needs a diplomatic solution at the higher level,” he said, but added that the armed forces would continue to support front-line troops and protect fishermen.

Gen Brawner, the US-educated chief of the 150,000-member armed forces of the Philippines, joined navy personnel in a wooden-hulled supply boat, the Unnaiza Mae 1, which brought Christmas gifts, food and other supplies to a small contingent of Filipino marines and navy personnel stationed aboard the BRP Sierra Madre at Second Thomas Shoal.

Although now crumbling with rust and holes, the slightly listing Sierra Madre remains an actively commissioned Philippine navy ship, meaning any assault on it would be considered an act of war.

It has become a fragile symbol of the territorial claims of the Philippines.

Gen Brawner said he conveyed President Ferdinand Marcos Jr’s Christmas greetings to the Filipino forces and shared with them a traditional rice lunch.

The United States has repeatedly warned it is obligated to defend the Philippines, its oldest treaty ally in Asia, if Filipino forces, ships or aircraft come under an armed attack, including in the South China Sea.

China has warned the US not to meddle in what it says is a purely Asian dispute.

The country has rejected all international condemnation and attempts at legal intervention, including a 2016 ruling by a UN-backed arbitration tribunal that invalidated China’s claims, leaving them without any legal basis.

China says it has a legal right to “defend its sovereignty” in keeping with its expansive claim to the South China Sea.