Hu Jintao tells China navy to prepare for warfare and both the Philippines and Vietnam have repeatedly accused China of overt aggression in the region. If you look at the BBC map you can understand why Vietnam and the Philippines are not happy about China moving into their waters. Apparently China is hoping to find oil and deposits there.
Not only from the East to West, Vietnam and the Philippines, China are claiming territorial waters as far south as in the proximity of Malaysia and Brunei. Obama is also moving into Australasia with his plans for a full Marine task force in Northern Australia. That's right Obama who promised to decrease military intervention not increase it.