China rammed and sank a Vietnamese fishing vessel in the disputed waters of the South China Sea and detained the crew, according to Vietnamese officials.

“This is the first time a Chinese ship has hit and sunk boats in our commune this year,” Nguyen Van Hai, a provincial Vietnamese official, said Friday.

The incident is a dramatic outburst of a simmering controversy that has major global ramifications, as China is claiming sovereignty over one of the most important shipping lanes in the world.

Chinese officials denied responsibility for the collision, which took place Thursday.

“The Vietnamese boat refused to leave and suddenly veered sharply towards the Chinese vessel,” Chinese Foreign Ministry spokeswoman Hua Chunying said Friday. “Despite its best efforts to keep clear, the Coast Guard vessel was struck at the bow. The Vietnamese fishing boat then took in water and sank.”

The incident took place near the Paracel Islands, the scene of a 1974 battle in which the Chinese military defeated South Vietnamese forces. Chinese Coast Guard and Vietnamese fishermen “have been playing a cat-and-mouse game” in the vicinity for years, but China has expanded its ability to track vessels in the region, according to a leading South China Sea expert.

“It’s surprising that they used so much force,” Gregory Poling, a senior analyst at the Center for Strategic and International Studies, told the Washington Examiner. “This is the new normal in the South China Sea: Nobody operates without China's permission, or, they face a real risk of a violent run-in with the Coast Guard or the Chinese militia.”

That’s the lesson even if Chinese forces didn’t intend to sink the ship by ramming it, as Poling surmised. One of the islands in the archipelago hosts a significant military platform. Satellite imagery has recorded the presence of at least one fighter jet, anti-ship cruise missiles, and surface-to-air missiles.

“The same Chinese increase in capabilities that explains why they're getting so much better at stealing everybody else's fish also explains why no U.S. Navy ship can pass through the South China Sea without being shadowed by a Chinese boat the entire way,” Poling added. "China sees everything that moves in the South China Sea, with the exception of subs, maybe.”

Vietnamese officials said that the Chinese Coast Guard ship seized the floundering eight-man crew after stopping two other fishing vessels from rescuing them from the water. Beijing maintained that China conducted “a rescue operation,” before demanding that Vietnam restrain the fishing operations.

“The Chinese side has expressed its grave concern and strong dissatisfaction to the Vietnamese side over this, and demanded that the Vietnamese side earnestly inform its fishermen and regulate their fishing activities,” the Foreign Ministry spokeswoman said.