China and the Philippines have each unfurled their national flags on tiny sandbars in the South China Sea, staking competing sovereignty claims in strategic waters seen as a potential flashpoint for global conflict.

Both countries have planted flags on a collection of sand bars, extending the clash over the area between Beijing and Manila, a U.S. ally

The competing claims are reigniting tensions in the South China Sea and coincide with joint military drills between the U.S. and the Philippines.