OT: Seven US aircraft carriers have been sunk in the past 30 years.

[RN7]

In 2006 the Chinese Navy Song Class diesel-electric submarine famously reached within striking distance of the USS Kitty Hawk undetected. However in naval exercises a total of seven US Navy aircraft carriers have reportedly been sunk by non-nuclear submarines.

1981: USS Eisenhower was sunk in NATO exercises in the Atlantic Ocean by Royal Canadian Navy Porpoise Class diesel-electric submarine built in Britain in the 1960's, and wasn't even detected by US Navy ASW assets.

1981: During the same exercise the USS Forrestal was also sunk by an unidentified diesel-electric submarine, probably a British Royal Navy submarine.

1989: USS America sunk in the Atlantic Ocean by Dutch Navy Zwaardvis Class diesel-electric submarine.

1996: USS Independence sunk by the Chilean Navy German built Type-209 Class diesel-electric class submarine in the Pacific Ocean.

1999: USS Theodore Roosevelt sunk by the Dutch Navy Walrus Class diesel-electric submarine in the Atlantic Ocean.

2003: Unidentified US Navy aircraft carrier sunk by two Royal Australian Navy Collins Class diesel-electric submarines in the Pacific Ocean.

2005: USS Ronald Reagan sank by Swedish Navy Gotland Class AIP submarine in the Pacific Ocean.

Many other US Navy ships have also been sunk in exercises by non-nuclear submarines. In 1999 the Dutch submarine that sank the USS Theodore Roosevelt also sank the exercise command ship USS Mount Whitney, a cruiser, several destroyers and the Los Angeles Class nuclear attack submarine USS Boise. In 2000 a Royal Australian Navy Collins Class diesel-electric submarine almost sank the USS Abraham Lincoln, and sank two US Navy nuclear attack submarines in the Pacific Ocean. In 2001 another Australian Collins Class HMAS Waller sank two US Navy assault ships in the Pacific, and during the same exercise a Chilean Navy submarine sank the Los Angeles Class nuclear attack submarine USS Montpelier twice. In 2002 another Australian Collins Class HMAS Sheehan hunted down and sank the Los Angeles Class USS Olympia, while in 2003 two Australian Collins Class sank two US Navy nuclear attack submarines and an unidentified aircraft carrier.

Although such losses were only in exercises and its possible that operational restraints were put on US naval forces during such exercises it highlights the fact that US Navy carrier battlegroups could be vulnerable to submarine attack. During the Cold War the principle objective of the Soviet Navy was to eliminate US naval air superiority. The principle means of doing that was through Soviet nuclear submarines which were the Soviet Union's primary naval asset, and followed/shadowed US aircraft carriers and trained to destroy them through conventional or nuclear means in wartime. In the Twilight 2000 timeline this could have led to huge American naval losses.