North Korea blew up the cooling tower of its nuclear reactor Friday afternoon to symbolize its commitment to nuclear disarmament, one day after declaring its atomic programs.
South Korea's MBC-TV, which sent a crew to the Yongbyon atomic complex, reported that the explosion had taken place but didn't give details.
The reclusive North had invited some 16 foreign journalists including TV crews to cover the event live.
Yongbyon, 96 kilometers north of Pyongyang, is at the heart of U.S.-led diplomatic efforts to shut down the North's nuclear program in exchange for energy aid and major diplomatic and security benefits.
The 30-meter-high cooling tower is the most visible symbol of the communist state's decades-old pursuit of nuclear weapons.
Its demolition is largely symbolic, as the reactor had already been shut down under a six-nation disarmament pact.
The explosion came just 20 months after Pyongyang shocked the world by detonating a nuclear bomb in an underground test to confirm its status as an atomic power.
The North's declaration is expected to end the stalemate in six-party negotiations.
U.S. President George W. Bush welcomed the move as an "important step" but said it was only the start of the process. ``We will trust you only to the extent that you fulfill your promises,'' he said.
Bush announced that the U.S. would partly lift some Trading With The Enemy Act sanctions. He notified Congress he was removing North Korea from the U.S. list of state sponsors of terrorism, effective after a 45-day review period.
U.S. Secretary of State Condoleezza Rice said the tower's destruction would mark a step toward disablement, something that has been ongoing for many months to prevent the North from making more plutonium for bombs.
``It is important to get North Korea out of the plutonium business, but that will not be the end of the story,'' she said in Kyoto, Japan, on the sidelines of a meeting of the Group of Eight industrialized countries. North Korea's nuclear declaration, which was delivered six months later than the country promised and has not yet been released publicly, is said to only give the overall figure for how much plutonium was produced at Yongbyon.