Mr. Obama landed at a U.S. air base south of Seoul early Sunday local time and is expected to meet with South Korean President Lee Myung-Bak later in the day.

　　North Korea's announced plan to launch what it calls an observation satellite on a long-range rocket next month is expected to dominate the nuclear security summit of more than 50 nations next week.

　　The United Nations, U.S., European Union, Russia and Japan have warned North Korea that the plan is in violation with U.N. resolutions and urged it to abandon it.  Even North Korea's ally China has expressed concern that such a rocket launch would undermine stability in the region.

　　The United States has said the launch would cancel an agreement with North Korea to send it a large shipment of U.S. food aid in exchange for halting its nuclear and long-range missile programs.

　　North Korea announced Saturday it would hold an annual parliamentary session April 13 amid preparations for the rocket launch.

　　The U.S. president plans to visit the demilitarized zone between North and South Korea within hours of arriving in South Korea's capital.

　　Deputy National Security Adviser Ben Rhodes said earlier this week that the main points of the DMZ visit are to show support for the more than 28,000 U.S. troops serving in Korea and to stress the U.S. security alliance with South Korea.

　　Rhodes said the president's message to North Korea is the same as it has been throughout his administration, that by meeting its obligations and denuclearizing, Pyongyang can follow a clear path to better relations with the international community.

　　The DMZ is considered one of the most dangerous places on earth, with heavily-armed North and South Korean forces aligned against one another.  The two have remained in a formal state of war since an armistice ended combat in the Korean War in 1953.

　　The White House says while in South Korea, Mr. Obama will hold various bilateral meetings, including talks with Chinese President Hu Jintao.  Mr. Obama also plans to meet with the leaders of Kazakhstan, Russia, South Korea and Turkey on the sidelines of the summit.  He is also expected to meet with Pakistani Prime Minister Yousuf Raza Gilani to review efforts to support an Afghan-led reconciliation process with the Taliban.

　　South Korea Saturday welcomed President Obama's nomination of Jim Yong Kim, Korean-born president of Dartmouth College, to head the World Bank.