China is loitering over undersea cables in “gray-zone” warfare against neighboring countries, as well as the U.S. and its allies, as it seeks to dominate the South China Sea. Several incidents, reported by Nikkei Asia, suggest the PRC is actively mapping the seafloor for vulnerabilities and using civilian research vessels to do so.

A serious incident in September, for instance, saw the Philippine Coast Guard respond to a Chinese research vessel close to an undersea cable. The vessel reportedly ignored radio contact while broadcasting a false ID before manoeuvring to evade capture. The Philippines, in response, sent its largest vessel to respond. That vessel was spotted 37 nautical miles away from the Batanes province, officially part of the Philippines but claimed by China. The incident also saw a Chinese coastguard ship intervene, with Beijing complaining of harassment afterward, according to the South China Morning Post.