U.S. warns Beijing on South China Sea

The U.S. has warned China that moving a drilling rig into seas disputed with Vietnam was "provocative". In a telephone call, U.S. Secretary of State John Kerry told Chinese Foreign Minister Wang Yi the U.S. had "strong concerns" over recent developments. Last week, Chinese and Vietnamese ships clashed over the drilling rig that China has placed in waters near the disputed Paracel Islands.
Background:
U.S. warns Beijing on South China Sea tensions [BBC]
China and Vietnam at impasse over rig in South China Sea [NYT]