June 19, 2006: Sweden has agreed to allow one of its subs, the Gotland, to spend a second year working with the U.S. Navy as part of an anti-submarine warfare training program. The diesel-electric Gotland is the first submarine designed from the start to use air-independent propulsion (AIP). The Gotland can remain submerged for 19 days and is among the quietest non-nuclear submarines in the world. The four Gotland class boats are highly automated, with a crew of 25. They displace 1,494 tons, are 190 feet long and have four 533mm torpedo tubes (with 12 torpedoes) and two 400mm tubes (with six torpedoes).

The Gotland has been based in San Diego, along with three dozen civilian technicians to help with maintenance. The U.S. Navy has also trained against Australian diesel-electric subs, and often come out second. The Gotland is more modern than the Australian boats, particularly because of its AIP system. Thus the Gotland is something of a worst case in terms of what American surface ships and submarines might have to face in a future naval war. None of America's most likely naval opponents (China, North Korea or Iran), have AIP boats, but they do have plenty of diesel-electric subs which, in the hands of skilled crews, can be pretty deadly.

Training against the Gotland enables the U.S. Navy to improve its anti-submarine tactics and techniques, as well as getting much valuable from inside the Gotland. All the results of this training is highly classified, but it has apparently been successful enough to extend the program for a year.