Chinese survey ship the Haiyang Dizhi 8 has returned to disputed waters in the South China Sea where it has been engaged in a month-long stand-off with the Vietnamese, according to a ship tracking analysis. Many observers speculated its departure was a brief refuelling or replenishment stop for the ship at Fiery Cross Reef, one of China’s artificial island outposts in the Spratlys, according to Collin Koh, a research fellow from Singapore’s RSIS. He said he did not believe that the ship had been pulled back as a concession by China, which objects to Vietnam’s oil exploration work in the region.