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 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.

A Chinese navy helicopter flew within 10 feet of a Philippine patrol plane on Tuesday in a disputed area of the the South China Sea, as the Filipino pilot warned by radio: “You are flying too close, you are very dangerous.