The Associated Press says there is a deepening suspicion that North Korea was involved in the sinking of South Korea’s “Cheonan” naval vessel.

AP on Monday quoted the U.S.-based think tank "Global Security" as saying that although the North Korean submarine force reflects dated technology by Western standards, the North’s submarines during wartime would present significant challenges, particularly in coastal areas.

AP also quoted a North Korea expert with "Jane's Information Group" as saying that the South Korean naval vessel is likely to have been attacked by a torpedo.

The expert reportedly added that North Korea's submarines and semisubmersibles can carry mines or torpedoes and that if the Cheonan was actually hit by a torpedo, it might have been an intentional attack.