The head of the U.S. Navy has warned China that hostile behavior from its coast guard and fishing boats will not be treated any differently from the Chinese navy, the Financial Times reported on Sunday.
In an interview with the FT, Admiral John Richardson said he told Chinese vice-admiral Shen Jinlong in January that Washington will respond to aggressive acts by these non-naval ships the same way it has with the People's Liberation Army Navy.
That's because non-naval ships have been used to help Beijing stake its claims in the disputed South China Sea, the London-based newspaper reported Richardson as saying.
"I made it very clear that the U.S. navy will not be coerced and will continue to conduct routine and lawful operations around the world," Richardson told the newspaper.
The warning from the U.S. Navy comes as China increasingly relies on its coast guard and maritime militia — or marine industry workers trained alongside its navy — to expand its military presence in the region.
According to a 2018 report from The Pentagon, Beijing's maritime militia is the only one in the world that has been sanctioned by the government, and it "plays a major role in coercive activities to achieve China's political goals without fighting."
The non-navy vessels have reportedly chased and fired water cannons at fishing vessels from Vietnam and the Philippines.
China has disputed territorial claims in the South China Sea with Vietnam, Taiwan, Malaysia, the Philippines and Brunei. While the conflict remains unresolved, the waterway has come up as a flash point in U.S.-China relations in recent years.
On Sunday, the U.S. military said that two of its navy warships sailed through the Taiwan Strait — which separates mainland China from the island of Taiwan, Reuters reported. Beijing regards Taiwan as a renegade province under its One China Policy, and opposes other countries pursuing diplomatic relations with the self-ruled island.
The U.S. Navy and the People's Liberation Army Navy did not immediately respond to CNBC requests for comment.