North Korea detonated a 60-foot-tall cooling tower above its main nuclear reactor complex Friday - the most visible symbol of its nuclear weapons program.
It was intended as a gesture of the country's commitment to stop making plutonium for atomic weapons.
Click the player to watch the tower's demolition and to hear comments from the U.S. State Department's Sung Kim.
The move comes just one day after President Bush said he would take steps toward lifting economic sanctions and removing North Korea from a list of terrorism-sponsoring countries.
As a crowd of dignitaries and international journalists watched, an explosion brought down the round tower in a mass of grey and white smoke.
"This is a very important step in the disablement process and I think it puts us in a good position to move into the next phase," said Sung Kim, the U.S. State Department's top expert on the Koreas who attended the demolition.
North Korea's Foreign Ministry also officially responded to the Bush Administration's decision to take the country off the U.S. trade and sanctions blacklists.
"The U.S. measure should lead to a complete and all-out withdrawal of its hostile policy toward so that the denuclearization process can proceed smoothly," the ministry said in a statement carried by the official Korean Central News Agency.
The explosion of the tower would represent the first step towards disablement said U.S. State Secretary Condoleezza Rice. The ultimate goal? Stop the North from creating 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.
The tower's destruction so far has been the highlight of disarmament talks between seven countries that have dragged on for more than five years.
North Korea's nuclear declaration, delivered six months later than promised, is said to only give the overall figure for how much plutonium was produced at Yongbyon - but no details of bombs that may have been made. It has not yet been released publicly.
It is the belief of experts that North Korea has made up to 110 pounds of weapons-grade plutonium. That's enough material for as many as ten nuclear warheads.
News of the declaration was being distributed to the other countries involved by China, the chair of the arms talks, according to U.S. envoy Christopher Hill.
"We'll have to study it very carefully and then we'll have to work on verification," Hill said in Kyoto.
The declaration does not include the North's alleged uranium enrichment program. It also fails to address suspicions of its nuclear proliferation to other countries such as Syria.
Source: The Associated Press