China and Vietnam are at odds over the South China Sea . Six countries claim the sea in whole or in part . The Philippines has been a key U.S. ally for decades, but Beijing is increasingly concerned about its growing military power as it tries to assert itself on disputed islands in the region. China rejects foreign intervention , but Vietnam has welcomed it .
China and Vietnam are at odds over the South China Sea . Six countries claim the sea in whole or in part . The United States says it is neutral but has offered to mediate . China rejects foreign intervention , but Vietnam has welcomed it .