MANILA, Philippines — A Chinese research vessel approached close to the Philippine coastline on Saturday morning before switching off its tracking system, a maritime security analyst reported.

Retired US Air Force Col. Ray Powell, director of the SeaLight project at Stanford University’s Gordian Knot Center, said that the Dong Fang Hong 3, a 103-meter oceanographic ship, came within 65 nautical miles of the Philippines before going “dark” at 7:12 a.m. local time.

The vessel is equipped with advanced oceanographic sensors, multi-beam sonar, and remotely operated vehicles, giving it the capability to conduct seabed mapping, acoustic monitoring, and surveys of underwater infrastructure, Powell noted.

He warned that such activities form part of Beijing’s “gray zone tactics playbook,” in which China mixes legitimate scientific research with assertion of its maritime claims and the gathering of potential military intelligence.

Chinese research vessel spotted near Philippine coast but 'goes dark' after, says maritime expert, This news data comes from:http://www.aichuwei.com

Powell’s post, citing tracking data from maritime analytics firm Starboard, comes amid continuing tensions in the West Philippine Sea, where Manila has repeatedly protested Chinese incursions.

As of posting time, Philippine authorities have yet to issue a statement on the reported movement of the Chinese vessel.