U.S. Secretary of Defense Robert Gates says his country and South Korea are considering conducting additional joint military exercises in the wake of North Korea’s sinking of the “Cheonan” naval ship.

Gates made the statement on Friday prior to attending the 9th International Institute for Strategic Studies Asia Security Summit.

Gates said North Korea "is more unpredictable than usual," adding that the U.S. is considering various moves, including conducting additional antisubmarine drills with the South.

Earlier on Wednesday, the Associated Press quoted defense officials as saying that the U.S. is considering dispatching the massive USS George Washington aircraft carrier to the waters where the Cheonan went down as a show of force.

However, Pentagon spokesman Geoff Morrell denied the report, saying that the U.S. has no immediate plans to dispatch aircraft carriers to South Korean waters.