The state-run Chinese Academy of Sciences only disclosed the pair of acoustic sensors earlier in January 2018, but had been operating them since 2016, according to a report from the South China Morning Post. One of them is in the Challenger Deep, located at the southern end of the Marianas Trench and the deepest known point on earth, and the other is situated further west near the island of Yap, part of the Federated States of Micronesia. Both reportedly can pick up acoustic signatures more than 620 miles away, putting them within range of Guam and the major strategic U.S. naval base at Apra Harbor.

The two devices are “a breakthrough for China,” the head of the deep-sea surveillance and communication programs at the Academy of Sciences, identified only by the surname Zhu, told the South China Morning Post. “The deeper under the surface, the quieter the world becomes, and it allows us to concentrate on the signal we most want to hear.”…..more here