"All great powers put sensor arrays at the bottom of the ocean for anti-submarine warfare," James Lewis, a former US government official and vice president at the Center for Strategic and International Studies, told the Hong Kong-based news outlet. "China has become a great power and is acting like one," Lewis added.
The sensors collect water temperature and salinity data that impact how sound moves through water, which ultimately enhances Beijing's capacity to keep tabs on US submarines. One of the sensors is situated on the floor of the Marianas Trench, the deepest part of the world's ocean, while the other is located off the coast of an island in Micronesia.
The sensors are both located within 500 kilometers of Guam and have a signal detection capability of 1,000 kilometers, according the Chinese academy in charge of overseeing the underwater surveillance program.
The surveillance network has watched the movements of the US Navy's fast attack nuclear submarines operating near Guam, according to the South China Morning Post.
However, Yu Yongqiang, a researcher who works on the panel overseeing the underwater surveillance network, stated last month that the surveillance network was dwarfed by systems the US operates. "We have just made a small step in a long march," Yu said.