Although I agree that U.S. aircraft carriers are extremely vulnerable to attack from DPRK submarines, I would like to point out that the sinking of the corvette, the ROKS Cheonan, in 2010 was highly controversial. At first the U.S. was covering up the fact that it sank during simulated live fire war games with South Korea. China and Russia dismissed the findings that the Cheonan was sunk in an attack by a DPRK sub. I followed the story very closely at the time, and to me, what seems most plausible was that the Cheonan explosion was a friendly fire incident during war games. Whether it was an accident or deliberate, I do not know.

In the Asia Times Online June 4, 2010, "Pyongyang: Cheonan was a false flag sinking", the North Korean author, Kim Myong Chol, claims the mine-laying USS Salvor, controlled by Military Sealift Command, was stationed close to Baengnyoung Island during anti-submarine warfare operations, and that navy seals planted a magnetic mine in a false flag event.