A People’s Liberation Army Navy (PLAN) amphibious warship allegedly rammed two Vietnamese fishing vessels operating near the disputed Spratly Islands in July, according to local press cited in an Office of Naval Intelligence threat to shipping report.

According to accounts of the fisherman, reported in the Nguoi Lao Dong newspaper, about 15 nautical miles off the western coast of the Spratlys on July 21 “a strange iron-clad Chinese ship numbered 994 suddenly appeared and approached [the fishing vessel] sounding its horn.”

The ship then sprayed the vessels with water cannon and precipitated a 30-minute chase.

“In order to avoid a possible collision, I tried to steer my boat away, but the strange ship still chased after and then rammed it on the right side,” captain Nguyen Nhat Ngoc said to the paper.

Ngoc descried the heavily armed Chinese vessel hit the ship twice more before breaking off the pursuit.

“Bui Thanh Ninh, another local fisherman, said his boat with 13 crew members suffered a similar attack also in the area on [July 23], by the same Chinese ship with code number 994,” reported Thanh Nien News.

According to the Office of Naval Intelligence (ONI) recently published PLAN and Chinese maritime law enforcement guide, the only vessel with the hull number 994 is the 4800-ton Yuting II Type 072A tank landing ship (LST) Daiyun Shan (994). The landing ship is more than 100 meters long.

Reports of the incident were collated in the July ONI Worldwide Threat to Shipping (WTS) Report. The report did not connect the hull number to a PLAN ship.

Navy officials told USNI News on Friday the inclusion of the incident in the report — a collection of open source information — carried with it no change in the U.S. stance toward Chinese actions in the South China Sea.

Vietnamese fishermen have reported an increase in confrontations with Chinese coast guard and civilian ships since a standoff between Beijing and Hanoi over the presence of a Chinese owned oil-rig for two months in Vietnamese claimed waters in 2014.

“The flare-up in incidents of Chinese vessels ramming Vietnamese fishing boats in recent weeks has come as Vietnam increases high-level contacts with the United States,” reported the The Diplomat in mid-July.

On Thursday, Secretary of State John Kerry gave an unvarnished criticism of China’s growing expansion into the South China Sea and the ongoing campaign to restrict access in the region.

“Freedom of navigation and overflight are among the essential pillars of international maritime law,” Kerry told the East Asia Summit in Kuala Lumpur according to a report in Reuters.

“Despite assurances that these freedoms would be respected, we have seen warnings issued and restrictions attempted in recent months.”

In addition to the uptick in maritime presence, China has also continued a campaign of land reclamation in the Spratlys, most notably constructing a 3,000 meter runway on reclaimed land on the Fiery Cross Reef near the Philippines.