Key Points and Summary: In 2004, Sweden’s Gotland-class submarine “sank” the Nimitz-Class USS Ronald Reagan aircraft carrier during a naval exercise, highlighting the potential vulnerabilities of U.S. supercarriers.
-And the craziest part: the Gotland-class submarine cost around $100 million to build, whereas the Ronald Reagan Nimitz-class aircraft carrier cost $4.5 billion to make.
-Equipped with air-independent propulsion (AIP), Gotland-class submarines operate silently and remain submerged for weeks, making them difficult to detect.
-The incident was a wake-up call for the U.S. Navy, leading to a lease of the Gotland for antisubmarine warfare training.
-However, China now fields 20 Yuan-class AIP submarines, presenting a new challenge for U.S. carrier groups.
-The Navy must apply lessons from the Gotland to counter threats posed by these advanced, stealthy submarines.
How Sweden’s Gotland-Class Submarine “Sank” a U.S. Aircraft Carrier
The US Navy has used aircraft carriers for power projection for over 80 years. With aircraft on board, they can sweep an enemy from the sea or bomb his troops and facilities on land.
But as fearsome and capable as carriers are, they are also the biggest target for our adversaries.
That’s why the carrier groups have so many support ships surrounding the carriers in a protective cocoon.
However, Sweden demonstrated in 2004, during an exercise, that a diesel-electric submarine equipped with air-independent propulsion (AIP) systems could sink one of America’s aircraft carriers. The Swedish submarine HSwMS Gotland with AIP “sank” the USS Ronald Reagan during the exercise, showcasing the stealth and endurance of these submarines.
And it wasn’t just once. During continuing exercises, the small Swedish sub could dart in and out of Reagan’s carrier group every time. And the excellent crew won every encounter. This was a huge wake-up call for the Navy’s carriers.
Sweden’s Gotland-class Submarines
The Gotland-class boats are small, crewed by only 32 officers and sailors. They are just 200 feet long and displace only 1,380 tons. Sweden possesses three Gotland-class diesel-electric attack submarines.
These submarines can travel up to 20 knots when submerged.
These Gotland-class subs were the first to feature a Stirling engine air-independent propulsion (AIP) system. Their weapons systems can fire torpedoes using four 533mm and two 400mm torpedo tubes. The Gotland was commissioned in 1996, and her sister boats, Uppland and Halland, joined the fleet in 1997.
The subs were designed to emphasize holistic stealth for operations in Swedish waters. The submarines are built to conduct antisurface and antisubmarine warfare, forward surveillance, special operations, and minelaying. The subs are very maneuverable due to the X-rudder system.
The Stirling Engine
The innovative Stirling engines can burn either oxygen stored in liquid oxygen tanks or standard diesel fuel. The subs are virtually silent and vibration-free, permitting weeks of undetectable underwater endurance.
This capability to operate for long periods underwater was once only reserved for nuclear-powered submarines.
The Gotland-class missions are only limited primarily by the quantity of liquid oxygen stored on board.
AIP allows a piston to move in a cylinder by rapidly heating and cooling the gas inside.
The engine cools down with cold seawater and heats up with liquid oxygen and diesel fuel. This efficient cold and heat system is unique to Gotland-class boats. It creates a quiet and fuel-efficient power plant.
The submarines also have two standard diesel engines that typically are used only for long-distance surface transits or while snorkeling. The submarines’ hydrodynamic hull minimizes noise and active sonar response, making it more difficult for enemy ships to locate.
The subs’ capabilities proved so innovative that the U.S. Navy coordinated to lease the Gotland after the “Reagan sinking” between 2005 and 2007. During that time, the HSwMS Gotland and her crew were based in San Diego, California, and operated as an opposing force in U.S. antisubmarine warfare training.

U.S. Navy Aircraft Carrier Ronald Reagan.
In 2018, the Gotland-class submarines were modernized by extending the bow by six feet. They included improvements to the sensor suite, an optronics mast, and upgrades to combat and data-management systems. The outstanding Stirling engines were upgraded, and the boat was modified to work in warmer waters.
Small But Lethal Gotland Submarines
Gotland-class submarines displace 1,580 tons surfaced and measure 203 feet with a 20-foot beam. Crew size ranges from 25 to 32 personnel. The armament consists of four 21-inch bow tubes for heavyweight Type 62 torpedoes and two 15.7-inch tubes for lighter-weight Type 45 or Type 47 torpedoes.
The smaller 15.7-inch tubes can be loaded with two torpedoes per tube. A total of 12 heavyweight and six lightweight torpedoes can be carried. Up to 48 mines can be transported using an external belt.

San Diego (Oct. 1, 2005) The Swedish diesel-powered attack submarine HMS Gotland transits through San Diego Harbor with the Nimitz-class aircraft carrier USS Ronald Reagan (CVN 76) following close behind during the ÒSea and Air ParadeÓ held as part of Fleet Week San Diego 2005. Fleet Week San Diego is a three-week tribute to Southern California-area military members and their families. U.S. Navy photo by Photographer’s Mate 1st Class Michael Moriatis (RELEASED)
Sweden has traditionally been a neutral country and never had a need for a large blue-water navy. Currently, Sweden only has five submarines, three in the Gotland class and two Södermanland-class subs. These were located in the Baltic to protect her shores in the event of a Russian invasion.
Putin’s belligerent Russia forced the Swedes’ hands. Sweden became a full member of NATO in 2024.
Now The Bad News
The Swedes aren’t the only ones with AIP submarines. China has built a Yuan-class submarine that operates with an AIP engine. China has built 20 submarines, which carry torpedoes and anti-ship missiles.
These submarines will be another worthy adversary if the US and China ever come to conventional war. Our carriers will have to use the lessons learned from the Gotland sinking of the USS Ronald Reagan if they wish to avoid that from happening again.
About the Author:
Steve Balestrieri is a 19FortyFive National Security Columnist. He served as a US Army Special Forces NCO and Warrant Officer. In addition to writing for 19FortyFive, he covers the NFL for PatsFans.com and is a member of the Pro Football Writers of America (PFWA). His work was regularly featured in other military publications.
