Vietnamese and Chinese ships have been embroiled in a weeks-long standoff near an offshore oil block in disputed waters of the South China Sea, which fall within Vietnam's exclusive economic zone, two US-based think-tanks say.
China's U-shaped "nine-dash line" marks a vast expanse of the South China Sea that it claims, including large swathes of Vietnam's continental shelf where it has awarded oil concessions.
The Haiyang Dizhi 8, a ship operated by the China Geological Survey, on Monday completed a 12-day survey of waters near the disputed Spratly Islands, according to separate reports by the Center for Strategic and International Studies (CSIS) and the Center for Advanced Defense Studies (C4ADS).
One of the oil blocks it surveyed is licensed by Vietnam to Spanish energy firm Repsol, which was forced last year and in 2017 to cease operations in Vietnamese waters because of pressure from China.
As the Haiyang Dizhi 8 conducted its survey, nine Vietnamese vessels closely followed it. The Chinese ship was escorted by three China Coast Guard vessels, according to data from Winward Maritime, compiled by C4ADS.
In a separate incident, the China Coast Guard ship Haijing 35111 manoeuvred in a "threatening manner" towards Vietnamese vessels servicing a Japanese-owned oil rig, the Hakuryu-5, leased by Russian state oil firm Rosneft in Vietnam's Block 06.1, which is 370km southeast of Vietnam.
That block is within the area outlined by China's proclaimed "nine-dash line".
"On July 2 the vessels were leaving the Hakuryu-5 when the 35111 manoeuvred between them at high speed, passing within 100 metres of each ship and less than half a nautical mile from the rig," CSIS said in its report.
In 2014, tension between Vietnam and China rose to its highest levels in decades when a Chinese oil rig started drilling in Vietnamese waters. The incident triggered boat rammings by both sides and anti-China riots in Vietnam.
In response to reports of this month's standoff, which first emerged on social media, Chinese foreign ministry spokesman Geng Shuang said on July 12 that China's position on the South China Sea was "clear and consistent".
"China resolutely safeguards its sovereignty in the South China Sea and maritime rights, and at the same time upholds controlling disputes with relevant countries via negotiations and consultations," Geng said.
On Tuesday, Vietnam's foreign ministry released a statement in response to unspecified "recent developments" in the South China Sea.
"Without Vietnam's permission, all actions undertaken by foreign parties in Vietnamese waters have no legal effect, and constitute encroachments in Vietnamese waters, and violations of international law," foreign ministry spokeswoman Le Thi Thu Hang said.
Australian Associated Press
