Chinese and Vietnamese law enforcement vessels had an extremely close encounter on 25 March near Vanguard Bank, as reported by Radio Free Asia along with Reuters and others. A look into historical automatic identification system (AIS) data from commercial provider MarineTraffic shows that, while this encounter was unusually dangerous, interactions between Chinese and Vietnamese vessels in the area have been a regular occurrence in recent months.
On 25 March, Vietnam Fisheries Surveillance (Kiem Ngu) 278 pursued China Coast Guard (CCG) 5205 as the latter patrolled oil and gas wells in the Nam Con Son basin, a critical area for Vietnamese offshore energy that supplies an estimated 13.5% of the country’s power needs.
CCG 5205 visited Chim Sao field in Block 12W, Lan Tay field in Block 06-1, Moc Tinh and Hai Thach fields in Blocks 05-3 and 05-2, and Lan Do field in Block 06-1, slowing but not stopping at each. Then it left the area heading southwest toward Vanguard Bank. When CCG 5205 stopped 13 nautical miles south of Vanguard Bank, Kiem Ngu 278 approached, and the two maneuvered at extremely close distances, with AIS indicating the two ships may have approached to within 10 m. Kiem Ngu 278 then followed the CCG vessel another 30 nautical miles south and had a similarly close encounter before the 5205 finally left the area, heading southwest into Malaysia’s exclusive economic zone.
A review of historical AIS data reveals that CCG vessels have been making regular passes through Vietnamese oil and gas concessions at Nam Con Son since at least last fall, with some evidence of occasional passthroughs dating back as early as May 2022.
With few exceptions, each Chinese ship was shadowed by either the Kiem Ngu or Vietnam Coast Guard (VCG) as it passed through Nam Con Son and when it left the area. But, though Vietnamese vessels were sometimes seen approaching within a few hundred meters, AIS data suggests that there hadn’t before been an encounter as close as that on 25 March.
This signals a break from past behavior. The CCG has been regularly patrolling Vanguard Bank since 2020 but had previously approached the Nam Con Son oil and gas fields only occasionally to make targeted challenges to specific development projects. It now appears that Nam Con Son has been added to the regular route of CCG vessels assigned to patrol duty at Vanguard. This is similar to the pattern off Malaysia’s Sarawak State, where CCG vessels stationed at Luconia Shoals consistently patrol nearby Malaysian oil and gas projects.