Tomorrow's stealthy subs could sink America's navy

The best deterrent against submarine attack is robust defense—but as little as surface sailors like to discuss it, that defense has seldom been less assured.

Modern diesel-electric submarines (SSKs) are very hard to detect. It’s not that SSKs with air-independent propulsion (AIP) systems are much quieter, but they mitigate the SSK’s drawback: lack of speed and endurance on quiet electric power. When the Swedish AIP boat Gotland operated with the U.S. Navy out of San Diego in 2005-07, the Navy’s surface ships turned up all too often in a photo album acquired by the submarine’s mast. The sub was so quiet, that it consistently managed to get within easy torpedo range.

AIP submarines are a high priority in the budgets of nations such as Singapore, Korea and Japan. Russia has struggled with its Lada-class boats, but persisted, and is selling them to China. Sweden, whose Kockums yard developed the AIP technology for Japan’s big 4,100-ton Soryu-class subs, had trouble getting its A26 replacement submarine program started. In an indication of its importance, Saab will buy the Kockums yard back for Sweden from ThyssenKrupp Marine Systems.