(VOVworld) – The US criticized the entry of Chinese oil rig HD 981 into Vietnamese waters in the East Sea as a provocative act that threatens regional stability.

CNOOC 981, the first deep-water drilling rig developed in China, is pictured at 320 kilometers (200 miles) southeast of Hong Kong in the East Sea

US State Department spokeswoman Jen Psaki told Washington reporters on Tuesday that the US is taking the issue under serious consideration: "Given the recent history of tensions in the East Sea, China's decision to operate its oil rig in disputed waters is provocative and unhelpful to the regional maintenance of peace and stability. Such activities pose the necessity for all related parties in the East Sea dispute to clarify their requirements in accordance with the international law”

Psaki wondered if the Chinese move is in response to US President Barack Obama’s recent visit to Asia, where he asked China to follow international laws on the East Sea. Daniel Russel, Assistant US Secretary of State for East Asian and Pacific Affairs, said the US was looking into the matter and urged caution on all sides.