"The Chinese Academy of Sciences recently disclosed that underwater acoustic sensors have been monitoring sea activity near Guam since 2016."
Source: Russia's SputnikNews relaying a Hong Kong, South China Morning Post report of
January 22, 2018.
The report indicates "The sensors collect water temperature and salinity data that impact how sound moves through water". These make the underwater acoustic (SOSUS) sensors more accurate AND also provides a scientific research "cover" for basically ASW sensors.
Once China perfects node sensors near Guam, and in the South, China Sea, China will lay 500+ km undersea SOSUS cable arrays, stringing many sensors together
- thereby providing electrical and communications channels to the sensors.
The main (near Guam) Chinese sensor targets would be the US Submarine Squadron 15 (SUBRON 15), at Naval Base Guam island.
Anderson Air Base (at right) is also on Guam island, as is Guam (Apra) Naval Base, where
SUBRON 15 has long been based. South China Sea on left. All "targets" for China's developing SOSUS systems.
SUBRON 15 mainly consists of:
- the large submarine tender USS Frank Cable (AS-40)
- four Los Angeles class SSNs, namely USS Key West (SSN 722), USS Oklahoma City (SSN 723),
USS Topeka (SSN 754) and USS Asheville (SSN 758).
- also an Ohio class SSGN occasionally visits.
FOR FURTHER BACKGROUND
See Submarine Matter's June 17, 2015 article, Guam Nuclear Submarine and Bomber Air Base.