China’s operations, including entering Vietnam’s exclusive economic zone (EEZ), increase the costs and risks for its neighbors namely Vietnam, Malaysia, and the Philippines to operate within the nine dash line.

Chinese survey vessel Haiyang Dizhi 8. Photo: Weibo

The de-escalation over the past years aims to harass Vietnam’s oil and gas Block 06-01, which is operated by Russia’s Rosneft, according to Washington-based non-profit organization Center for Strategic and International Studies (CSIS).

In early July, Chinese survey vessel Haiyang Dizhi 8 along with its coast guard and paramilitary escorts entered Vietnam EEZ and left the zone after nearly four months.

The standoff began on June 16 when a China Coast Guard (CCG) ship started harassing Hakuryu 5 oil rig (Russian oil major Rosneft holds the rights for the block off the coast of Vietnam’s Vung Tau) and the offshore supply vessels servicing it.

China's militarization within Vietnam's territorial waters catches international protest. Photo: CSIS

Automatic Identification System (AIS) data shows that several CCG ships were deployed in succession to keep up the harassment over the course of the standoff. As ships were relieved, they often traveled to the Chinese outpost on Fiery Cross Reef to resupply before either joining the escort mission around the Haiyang Dizhi 8 or heading back to China, CSIS said in a recent report.

Exactly how many Chinese and Vietnamese vessels were involved in these two related operations over the course of the standoff is unclear. In October, Vietnamese Major General Nguyen Minh Hoang announced that 50 Vietnamese and 40 Chinese vessels were involved, while others reported as many as 80 Chinese participants, the report read.

Hakuryu 5 oil rig. Photo: Japan Drilling Co

As for the Haiyang Dizhi 8, it moved north after the first few weeks of the standoff, extending its survey over a much wider area for the next three months. In hindsight, it is clear that the survey area closely matched a group of oil and gas exploration blocks that China National Offshore Oil Corporation unsuccessfully offered up for foreign bidding in 2012.

Over the course of the standoff, the Haiyang Dizhi 8 and its CCG escorts made multiple resupply trips to Fiery Cross Reef, according to CSIS which seeks to advance global security and prosperity by providing strategic insights and policy solutions to decisionmakers.

On August 26, the US Department of Defense said it is greatly concerned by China’s coercive interference in Vietnam's longstanding oil and gas activities in the South China Sea.

Chinese actions to coerce ASEAN neighbors, station offensive military systems, and enforce an unlawful maritime claim raise serious doubts over China’s credibility, the Pentagon said, adding “The United States will continue to support efforts by our allies and partners to ensure freedom of navigation and economic opportunity throughout the entire Indo-Pacific.”