[img]http://d.yimg.com/a/p/ap/20100725/capt.e97cf6b5a4a94578a73169eb41535aba-e97cf6b5a4a94578a73169eb41535aba-0.jpg?x=116&y=130&q=85&sig=DZefh7g9knkCvE_rL95eMA--[/img]AP - A massive nuclear-powered U.S. supercarrier began maneuvers Sunday with ally South Korea in a potent show of force, four months after the sinking of a South Korean warship. North Korea threatened the exercises could lead to nuclear war.