U.S. President Barack Obama is on his way to South Korea for next week's Nuclear Security Summit. He flew out of the Washington area on Air Force One in the early Saturday morning darkness.Obama will join more than 50 world leaders for the high profile summit in South Korea's capital, Seoul. The meeting comes as North Korea threatens to stop the progress made toward nuclear disarmament, with plans to launch a long-range rocket next month. The United States said last week the rocket launch would cancel an earlier agreement with North Korea for food aid in exchange for halting its nuclear and long-range missile programs. The White House says Obama will hold various bilateral meetings, including talks with Chinese President Hu Jintao. Obama also plans to meet with the leaders of Kazakhstan, Russia, South Korea and Turkey on the sidelines of the summit. A White House statement Friday said President Obama will meet with Pakistani Prime Minister Yousuf Raza Gilani to re...