This time it's about the the southern part of the Paracel Islands [西沙群岛] and namely the maritime area of Triton Island [中建岛]. That area was subject of a short war in 1974 when the former republic of South Vietnam lost it to China. Some islands are still disputed because the Democratic Republic of Vietnam views itself as a legitimate follower of former U.S. satellite South Vietnam and has renewed old territorial claims.
The Chinese side has voiced its position on cobalt mining platform "981", advising Vietnam not to provoke again.
China News Network reported on June 8:
Today's subject on the website of [China's] ministry of foreign affairs is "the operation of cobalt mining platform 981: Vietnam's provocation and China's position". The foreign office states the Xisha Islands are China's long-standing territory which is far from any dispute whatsoever. [However,] armed vessels embedded in [regular] shipping and dispatched by Vietnam are illegally forcing and disturbing the operation of China's cobalt mining platform 981. Furthermore, [Vietnam] is winking at its interior demonstration against travelling Chinese. The Chinese side is exercising utmost restraint towards provocative activity from the Vietnamese side, and China admonishes Vietnam to proceed from an overall [aspect] of upholding both countries' relations and stabilizing peace in the South [China] Sea, such mitigating a tense situation and restoring tranquility on the sea as soon as possible.
[Source: China News Network 中新网 quoted by 华广网 on June 8, 2014]
Diaoyu-Island (Japanese: Senkaku) is disputed between China and Japan.
That dispute only recently lead to a heated bilateral crisis, even though, there
are neither crude oil nor natural gas nor valuable minerals known in the area.