A Philippine plane warned a Chinese military helicopter over the South China Sea that it was "flying too close," as tension between the U.S. ally and Beijing soars.

A Chinese navy helicopter has flown within 10 feet of a Philippine patrol plane in a disputed area of the the South China Sea, highlighting Beijing's use of force in asserting its claims to the strategic waterway.

A Chinese military helicopter flew within 10 feet (3 meters) of a Philippine patrol plane over the South China Sea on Tuesday, in what observers said was the second incident of potentially catastrophic behavior by the People’s Liberation Army against foreign aircraft in a week.