Amid new tension with North Korea over a planned rocket launch, President Barack Obama plans to visit the Demilitarised Zone separating North and South Korea at the start of an international trip next week, the White House said, this Tuesday.

Sunday's trip to the most heavily defended border in the world carries obvious Cold War symbolism as Obama tries to foster new nuclear disarmament talks with North Korea. Although US officials regularly go to the DMZ, the presidential visit is likely to be read by the North as a special show of strength to its new, untested leader.

"The DMZ is the frontline of democracy in the Korean peninsula," and a symbol of US unity with military ally South Korea, said Daniel Russel, Asia director for the White House National Security Council. "A visit by the president there to see and to thank the US and the South Korean service members makes perfect sense."

Obama aides noted that Obama's visit comes almost exactly two years after the sinking of a South Korean warship, which Seoul and Washington blame on the North Koreans.

Obama will visit some of the approximately 28,500 US troops stationed in South Korea as a legacy of the Korean war six decades ago. The DMZ trip is his first stop on a three-day visit to Seoul, South Korea, for an international summit on keeping nuclear weapons materials out of the hands of terrorists.

The gathering of more than 50 nations is intended to take stock of progress towards Obama's goal of locking down nuclear material around the world by 2014. Despite some progress by known nuclear nations, the goal of complete security is far distant. It also is overshadowed by North Korea's nuclear brinksmanship and fears that Iran could soon build a nuclear weapon.

North Korea has built and tested nuclear devices and is suspected in the spread of weapons of mass destruction to other countries. North Korea is not invited to the security gathering.

"The nuclear security summit is not about North Korea," Russel said. "It's about the commitment of the participating nations to honour their pledges and their commitments." He said North Korea "will be the odd man out”.

Obama will hold separate discussions Monday and Tuesday with leaders of Russia, China, South Korea and other nations. It will be his last meeting with Russian President Dmitry Medvedev, who leaves office on May 7. Russia and China have blocked a US-backed effort to condemn Syria at the United Nations for its yearlong crackdown on civilians.

The Korean peninsula remains in a technical state of war since the 1950-53 Korean war ended in an armistice.