President Barack Obama travels to South Korea Saturday on a three-day trip centered on an international nuclear security summit in Seoul.
He is due to arrive in Seoul early Sunday, where he will later hold a bilateral meeting with his South Korean counterpart Lee Myung-bak.
Top officials from 54 countries, including China and Russia, will attend the summit meeting on Monday and Tuesday.
But its message of international cooperation has been overshadowed by North Korea's announcement last week that it is planning to carry out a rocket-powered satellite launch in April.
South Korea has said it considers the satellite launch an attempt to develop a nuclear-armed missile, while the United States has warned the move would jeopardize a food-aid agreement reached with Pyongyang in early March.
President Lee has already said he will use the summit to drum up international support against the actions of his northern neighbor.
North Korea says it has a right to a peaceful space program and has invited international space experts and journalists to witness the launch.
North Korea's state-run Korean Central News Agency (KCNA) cited a spokesman from the Secretariat of the Committee for the Peaceful Reunification of Korea as denouncing the South for working to turn the summit "into a platform for (an) international smear campaign" against the North.
The North has a right to a nuclear deterrent and to conduct a "satellite launch for peaceful purposes," the committee's statement said, and will take "counter-measures" if the South stirs up international criticism of its actions.
Against that tense backdrop, Obama will on Sunday morning visit the demilitarized zone that splits the Korean Peninsula in two for the first time.
He will also meet with some of the 28,500 U.S. troops stationed in South Korea, two of his top national security advisers said Tuesday during a conference call.
Although Obama himself has not been to the demilitarized zone during his two previous trips to South Korea as president, Secretary of State Hillary Clinton paid a visit to the area in 2010.
And Obama's predecessor, George W. Bush, used binoculars to peer into North Korea from a sandbagged bunker on the southern side of the border in 2002.
The date of Obama's visit " is virtually two years to the day" since the sinking of the South Korean warship, the Cheonan, which left 46 Southern sailors dead, said Daniel Russel, director for Japan, South Korea, and North Korea at the U.S. National Security Council.
South Korea says a North Korean torpedo attack was to blame for the ship's sinking. The North has denied the accusation.
In a dramatic reminder of the U.S. military presence in South Korea, an American F-16 fighter jet crashed Wednesday near Kunsan airbase on the western coast of South Korea.
The jet's pilot safely ejected before the crash, and no casualties were reported, said Maj. Eric Badger, public affairs officer of the 7th Air Force.
Seoul's nuclear summit will be the second after Obama hosted the first meeting in Washington in 2010. He initiated the biennial summit after presenting his vision of a nuclear-free world in Prague in April 2009.
The official agenda will deal with nuclear terrorism and how to secure the world's nuclear material.
Although North Korea is not on the agenda, it is likely to be discussed on the sidelines.
Pyongyang announced earlier this month it would carry out a "satellite launch" in mid-April to commemorate the centenary of the birth of Kim Il Sung, the country's founder.
Using ballistic missile technology, however, is in violation of U.N. Security Council Resolution 1874 and against a deal struck with the United States earlier this month that it would not carry out nuclear or missile tests in return for food aid.
Pyongyang has said it will see any critical statement of its nuclear program as "a declaration of war."
Concerns about Iran's nuclear program, again not on the official agenda, will also be discussed in bilateral meetings between leaders.