It's news because it changes the balance of power in the South China Sea, waters that China has been gradually asserting are its own territorial waters rather than international waters governed by the United Nations. This assertion has China and the U.S. inching towards military confrontation, because if China's assertions become
de facto reality Western sea and air access to important regional trade partners like Taiwan, the Philippines and Vietnam could be limited or cut off completely whenever Beijing feels like it.
There's a good timeline on how things have been playing out here: http://www.latimes.com/world/asia/la-fg-south-china-sea-time...