Naval technologies have advanced on many fronts, but one of the most significant is the growing roster of diesel-electric submarines that boast exceptional quietness. Some of the newer AIP (Air-Independent Propulsion) models even have the ability to operate without surfacing for a week or two at a time. In exercises against the US Navy, diesel-electric submarines have successfully ‘killed’ their nuclear counterparts, and in 2006, a Chinese submarine reportedly surprised a US carrier battlegroup by surfacing within it.
The US Navy is slowly moving to beef up anti-submarine capabilities that had been neglected since the end of the Cold War, and other navies are also beginning to adjust. One of the first areas that requires attention is improved detection. That means wider coverage areas, longer baselines, better sonar and other detection systems, and greater use of small unmanned platforms on the surface and underwater. With UUV/USV platforms still maturing, and almost every advanced navy except the Chinese getting smaller due to the cost of new warships, towed systems are a natural place to start.