https://www.popularmechanics.com/mi...75/gotland-class-sub-ronald-reagan-war-games/
"By the mid 2000s, other countries were starting to field or develop AIP capable diesel-electric submarines, including Russia and especially China. Since the US Navy had retired its last diesel-electric (non-AIP) attack submarine in 1990, the
USS Blueback (now a local resident here at Oregon’s Museum of Science & Industry) there was no indigenous force to practice hunting down diesel-electric subs, let alone ones with advanced AIP capabilities. Thus the U.S. Navy went to Sweden hat in hand in hopes of leasing one of their ninja-like
Gotland Class boats and its crew for a year.
The Swedish sub would be playing the adversary to America’s massive constellation of anti-submarine surface combatants, helicopters, fixed wing aircraft, and especially nuclear submarines. The Swedes granted this request and the
Gotland was shipped to San Diego aboard a mobile drydock.
By mid-summer of 2005, the
Gotland arrived in San Diego and war games immediately commenced. Apparently, the Navy got more than they were bargaining for when it came to finding and engaging the stealthy little sub. The
Gotland virtually “sunk” many US nuclear fast attack subs, destroyers, frigates, cruisers and even made it into the ‘red zone’ beyond the last ring of anti-submarine defenses within a carrier strike group.
Although it was rumored she got many simulated shots off on various U.S. super-carriers, one large-scale training exercise in particular with the then brand new USS
Ronald Reagan ended with the little sub making multiple attack runs on the super-carrier, before slithering away without ever being detected.
One contact of mine within the anti-submarine community said that the
Gotland was the single biggest eye opener of their career. The Swedish sub was “so silent it literally did not exist to our sensors.” Apparently, its crew knew exactly how to employ her strengths to devastating effects as that same contact described the sub as “a vastly demoralizing capability that changed the priorities within the surface and sub-surface warfare communities.”
Once the first year of the lease ran out, the Navy quickly arranged another year on the contract to sort through tactics to deal with this proliferating yet unassuming and deadly threat. It wasn’t until mid-2007 that the
Gotland finally loaded up on its mobile drydock and headed back to its home on the Baltic Sea. "
http://www.thedrive.com/the-war-zon...rier-killing-sub-just-got-some-major-upgrades