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.

The Philippines and Japan pledged to enhance their defense alliance through training exercises, logistical activities, equipment transfers and intelligence sharing on Monday amid China’s assertive moves in the South China Sea.

China's activity in the contested South China Sea is "hindering" Filipino companies from exploring natural resources in the region, Philippines Foreign Secretary Enrique Manalo said during a talk at Chatham House in London on Tuesday.

Disputed South China Sea airspace that Beijing claims as its own falls within Manila’s Exclusive Economic Zone, where the Philippines and other countries enjoy freedom of overflight.

Maritime tensions between China and the Philippines were in the spotlight at the Munich Security Conference, with former Chinese Vice Foreign Minister Fu Ying calling the occupation of disputed features in the South China Sea “a red line.”

Vietnam has quietly expanded its foothold in the South China Sea. Unlike with China, the rest of the region is turning a blind eye. The post Vietnam Is Also Expanding Its Foothold in the South China Sea appeared first on World Politics Review.