The United States sent China a warning after one of its ships used a laser to intimidate the Philippines.
The State Department said it would defend the Philippines in the event of an attack after China's laser temporarily blinded some coast guardsmen.
The skirmish occurred on February 6 near the Spratley Islands, a disputed island chain in the South China Sea.
A Chinese coast guard vessel shined a laser that briefly blinded members of the Philippines' coast guard who were on a resupply mission to the Second Thomas Shoal. Filipino forces are stationed there on a marooned former American vessel, the BRP Sierra Madre.
China's ship also came within 500 feet of the Philippine coast guard ship BRP Malapascua.
The Philippines condemned the incident as a "clear violation" of "Philippine sovereign rights," but China says the shoe is on the other foot.
"We hope the Philippines will earnestly respect China’s territorial sovereignty and maritime rights and interests in the South China Sea and avoid any actions that may lead to the expansion of the dispute and complication of the situation,” Chinese Foreign Ministry spokesperson Wang Wenbin said.
The use of the laser was an escalation from China's ordinary maneuvers, the Philippines said.
The State Department warned China that the U.S. would respond with force to attacks on the Philippines, a U.S. ally.
Spokesman Ned Pirce said China's "dangerous operational behavior directly threatens regional peace and stability, infringes upon freedom of navigation in the South China Sea as guaranteed under international law and undermines the rules-based international order."
“The United States stands with our Philippine allies,” spokesman Ned Price said in a statement.
Tensions between Washington and Beijing have been climbing over China's territorial claims over Taiwan and the South China Sea, which is disputed by the Philippines, Vietnam, Malaysia, Taiwan and Brunei.
The U.S., while not officially a party to the maritime disputes, deploys Navy vessels in "freedom of navigation" missions that China considers provocative.
Biden warned last year that the U.S. would intervene if China invades Taiwan, which China claims as its own.
The Biden administration has taken criticism for its delayed response to shooting down a Chinese spy balloon that traversed the continental U.S. earlier this month. Biden waited several days to down the balloon, which was equipped to intercept signals near U.S. missile sites.
Biden said after the brazen incursion that it wasn't a "major" breach.