The captain of the aircraft carrier USS John F. Kennedy has lost his job because his ship hit a much smaller wooden ship (a dhow) in the Persian Gulf last July. The incident, which happened at night,  is still under investigation, and points out how vulnerable U.S. Navy ships are in the crowded Persian Gulf. American warships are supposed to be particularly vigilant since the U.S. destroyer Cole was badly damaged in 2000 in Yemen by a small boat full of explosives. The USS John F. Kennedy is considered something of an unlucky ship. In 2001 its captain was relieved because the ship flunked an inspection.