N.Korean Subs 'Could Sink U.S. Aircraft Carrier'

North Korea's conventional weapons remain the biggest threat to the South Korean and U.S. militaries, experts say.

Burwell Bell, who was the commander of the U.S. Forces Korea from 2006 to 2008, said the denuclearization of North Korea is "but a part of problem. The major problem is that [North Korea] has conventional army of extraordinary size."

He warned that nobody can guarantee the safety of tens of millions of people in Seoul and vicinity or peace on the Korean Peninsula unless the North removes troops and artillery units from the demilitarized zone, he added.

Meanwhile, in an article for the National Interest, James Holmes, a professor of maritime strategy at U.S. Naval War College, claimed North Korean subs are capable of sinking a U.S. aircraft carrier under certain circumstances.

He said that it would be technically difficult to detect diesel-powered North Korean subs if they drift slowly after cutting their engines.

The North has some 70 subs.