Originally published on April 13, 2014. China has begin installing sensitive hydrophones on the floor of the China Seas in an effort to detect...

Originally published on April 13, 2014.

China has begin installing sensitive hydrophones on the floor of the China Seas in an effort to detect and track submarines belonging to the U.S. and its allies.

Lyle Goldstein and Shannon Knight, both highly-respected naval analysts, described the new listening system as “startling” in a recent article in Proceedings, a naval professional journal.

They claimed the “fixed ocean-floor acoustic array” is evidence that Beijing has begin to take seriously the incredible destructive power of enemy submarines—especially American ones.

China’s hydrophone system, which first appeared in 2012, apparently copies America’s own Sound Surveillance System, or SOSUS—an extensive network of hydrophones that helped the U.S. Navy track virtually all Soviet submarine movements starting in the mid-1950s.

The Soviets learned about SOSUS from American turncoat John Walker in 1968 and subsequently upgraded their sub designs to be quieter. In turn, the U.S. Navy enhanced SOSUS with better hydrophones and trawler vessels towing sensitive sonars.

At its peak effectiveness, SOSUS could detect submarines thousands of miles away. The hydrophone network was America’s “secret weapon,” according to the Navy—even when it wasn’t technically secret any more.

If China’s listening system is even half as effective as SOSUS, it could spell trouble for the U.S., Japanese and Australian navies, among China’s other rivals. The U.S.-led alliance’s numerous, high-tech submarines are its greatest advantage over Beijing’s rising military—and the surest guarantee against Chinese aggression.

If Beijing can reliably track American and allied subs, it can hunt them and potentially destroy them in wartime, thus defeating Washington’s first line of defense in the Pacific.

To be sure, there’s more to setting up a listening array than merely planting hydrophones in the seabed. SOSUS owed its success to steady investment and constant improvement over a period of 40 years—not to mention the U.S. Navy’s careful cultivation of a cadre of specialists able to interpret the array’s data output.

China has just begun setting up its own “Sino-SOSUS”—and could need years or decades to refine the related technology and techniques.

In any event, the Chinese array is an important step for a country that traditionally has neglected the difficult, expensive practice of tracking enemy submarines. As recently as 2011, Owen Cote—a naval analyst at the Massachusetts Institute of Technology—assessed Beijing’s anti-submarine warfare abilities as “very limited.”

China “appears not to be making major investments to improve” its sub-hunting prowess, Cote added.

That was then. Three years later, “the massive Chinese military-industrial complex has now come around to the great importance of ASW,” Goldstein and Knight wrote. “China’s substantial military and science-research energies have shifted accordingly.”