Following a request by the Japanese government, the city of Ishigaki in Okinawa Prefecture has agreed to call off a planned aerial survey of the Senkaku Islands within its city limits in the East China Sea, several knowledgeable sources said Tuesday. The decision is said to have been made to avoid worsening Japan-China relations. China asserts its own territorial claim to the uninhabited, Japanese-administered islets southwest of Japan’s mainland, calling them Diaoyu. Ishigaki authorities had planned to carry out the environmental survey by the end of the year using chartered civilian aircraft. Previously, the government refused to grant permission to Ishigaki authorities to go ashore on the islets for an environmental survey in 2010, when the now-opposition Democratic Party of Japan was in power. The restriction on the flyover was made despite previous statements by Prime Minister Shinzo Abe that the islets and the airspace above them are firmly under Japan’s administrative control. In November last year, China established an air defence identification zone over a swathe of the East China Sea including the Senkakus, warning that flying into the zone without prior submission of flight plans would result in the scrambling of fighter jets. This heightens the risk that chartered planes and Chinese military aircraft could come dangerously close over the islets. According to the sources, a high-ranking official at the Environment Ministry called Ishigaki Mayor Yoshitaka Nakayama to Tokyo on Dec. 15 to request he call off the survey, saying they ”cannot exclude the possibility that (the flyover) could lead to unforeseen events.” The ministry lacks the authority to order a stop to the survey, but the city agreed to call it off out of respect for the government, which ultimately controls the Senkakus, the sources said. Ishigaki authorities had decided earlier in the year to carry out the survey by having specialists take aerial photographs of the islets from a chartered plane. The city set aside 30 million yen in its fiscal 2014 budget for this purpose, and selected a contractor in July. Concerns for the environment on the Senkakus have mounted amid indications that an out-of-control goat population is destroying plant cover, putting the ground at risk of giving way. Little is known about the state of species endemic to the islets, including moles and azaleas.