China has constructed three new oil and gas platforms in the East China Sea over the past year, drawing formal protests from Japan. But tracking data of Chinese mobile drilling rigs and survey ships shows that Beijing may be planning to expand the geographic footprint of its operations into waters even more sensitive for Tokyo, increasing friction with Japan.
New Platforms
Beijing has built three new permanent platforms in the East China Sea since AMTI’s August 2025 survey of Chinese oil and gas activity in the area.
The locations of these new platforms match up with areas in which China conducted exploratory drilling from 2022 to 2025. Automatic identification system (AIS) data and satellite imagery show that the first was completed in late August 2025, when the crane ship Lan Jing 7500 constructed a fixed platform that has since been serviced by the jack-up rig Zhenhai 6. The Lan Jing 7500 then installed a second platform in January 2026, which has since February been serviced by the jack-up rig Haiyang Shiyou 942. And in April, crane ship Tiejian Qizhong 5000 constructed a third fixed platform, which has since been serviced by jack-up rig Dongfang Faxian (which previously broadcast under its English name, Oriental Discovery).
Tokyo has long protested Beijing’s oil and gas development in the area, arguing that China is tapping into hydrocarbon reserves that straddle the median line between the two countries and should therefore be shared. Beijing and Tokyo agreed to establish a joint development zone in the area in 2008 to help address this concern but it has never been operationalized. Instead, between 2013 and 2015, China built a dozen platforms along the median line just south of the zone. Under Japan’s domestic law, Tokyo treats the median line as a provisional boundary pending delimitation of the two countries’ overlapping continental shelf claims. Beijing does not recognize the median line but has thus far kept its development activities (barely) on the Chinese side.
Exploration Near the Joint Development Zone
Along with new fixed platforms, Beijing has also been active in exploratory drilling. Mobile jack-up rig Kantan 7 was observed operating at two new sites between China’s existing platforms in the fall and winter of 2025. More provocatively, from December to May, a jack-up rig was seen operating along the edge of the China-Japan joint development zone.
The jack-up rig involved was not captured broadcasting AIS, though several support ships such as the Kantan 303 and Haiyang Shiyou 642 were. The rig was, however, visible in satellite imagery from December 28 through May 1.
Jack-up rig and support ships operating near the joint development zone, April 5, 2026
Surveys North and South
There are also other signals that Beijing is looking to expand its East China Sea oil and gas operations. Two geological survey ships, the Haiyang Dizhi 8 and 9, conducted three seabed surveys of the area in the past year: two in the southern vicinity of Beijing’s existing platforms, and one much further north, again near the joint development zone.
The Haiyang Dizhi 8 has featured prominently in oil and gas-related tensions in the South China Sea, where it has conducted surveys in both Vietnamese and Malaysian waters.
With past exploration often a predictor of future platform construction, Beijing’s recent activity northwest of the joint development zone is likely a harbinger of more to come—and of increasing China-Japan tensions in the East China Sea.
