"...rendering the wine-dark sea transparent to hostile antisubmarine (ASW) forces for the first time..."
Hmm, from that sentence I speculate the US to have found a device most probably airborne device that's capable of detecting a submarine target in a wide area.
Probably a sea penetrating radar like device either on aircraft or satellite.
Hmm?!
http://gentleseas.blogspot.co.id/201...ubmarines.html