PYONGYANG , North Korea ( CNN ) -- North Korea on Friday destroyed a water cooling tower at a facility where officials acknowledge they extracted plutonium to build nuclear weapons , CNN 's Chief International Correspondent Christiane Amanpour reported from the scene . The cooling tower is demolished at the Yongbyon nuclear complex near Pyongyang , North Korea . The massive implosion , which came at about 5pm local time Friday at the Yongbyon facility , was intended to be a powerful public symbol of a move to end nuclear activities by the Communist nation once branded a member of an `` axis of evil '' by U.S. President George W. Bush . The destruction of the highly visible symbol of North Korea 's long-secret nuclear program came just a day after the country released details of its program . `` They fired a warning flare and then in three minutes the whole thing came tumbling down in a massive cloud of smoke , '' Amanpour said . Watch Amanpour 's report from the scene . » . `` There was a moment of stunned silence as the magnitude of what had happened sunk in , '' Amanpour said . U.S. State Department officials and observers from the International Atomic Energy Agency ( IAEA ) watched from a reviewing stand on a ridge about 1,000 yards away , she said . `` This is a very significant disablement step , '' the U.S. envoy to North Korea , Sung Kim , said . Nuclear experts say that the plant 's destroyed central water-cooling tower would take a year or longer to rebuild if North Korea were to try using the plant again . `` This is a critical piece of equipment for the nuclear reactor , '' said analyst John Wolfsthal , of the Center for Strategic and International Studies , who has been following North Korea since the 1980s . `` Without this facility , the reactor ca n't operate and ca n't produce more plutonium for weapons . '' Watch the tower being demolished » . North Korea has been dismantling other parts of the facility under the watchful eyes of representatives of the five other nations , including the U.S. , that have been involved in six-party talks aimed at ending Pyongyang 's nuclear weapons program . On Thursday , North Korean officials turned over to China a 60-page declaration , written in English , that details several rounds of plutonium production at the Yongbyon plant dating back to 1986 . Watch President Bush claim progress over the N. Korea nuclear issue » . In it , North Korea acknowledges producing roughly 40 kilograms of enriched plutonium -- enough for about seven nuclear bombs , according to the U.S. State Department . In response , Bush said he would lift some U.S. sanctions against North Korea and remove the country from the State Department 's list of state sponsors of terrorism . But he made clear that other sanctions remained in place on North Korea -- which has been on the terrorism list since its alleged involvement in the 1987 bombing of a South Korean airliner which killed 115 people . `` The United States has no illusions about the regime in Pyongyang , '' Bush said . `` We remain deeply concerned about North Korea 's human rights abuses , uranium enrichment activities , nuclear testing and proliferation , ballistic missile programs and the threat it continues to pose to South Korea and its neighbors . '' U.S. analysts will pore over the document to resolve Washington 's outstanding concerns , which include questions about the extent of North Korea 's proliferation of nuclear technology and the status of any uranium enrichment program . Watch what 's still unknown after Pyongyang 's declaration » . Friday 's event at the nuclear plant marked at least an effort by North Korea -- dubbed `` The Hermit Kingdom '' in the international community for its isolationist tendencies -- to show the world a good-faith effort to end its nuclear weapons program . Media outlets from the five other nations involved in the talks were invited to view the tower 's implosion , a rare move in North Korea . CNN was among the media outlets present . But there appeared to be no mention of the declaration or planned implosion at Yongbyon on the Web site of North Korea 's state-run news agency on Thursday . And an article Wednesday noted the 58th anniversary of the Korean war , calling it `` a war of aggression started by the U.S. imperialists in an attempt to occupy the whole of Korea . '' CNN 's Chief International Correspondent Christiane Amanpour contributed to this story from Pyongyang .
North Korea has a highly visible tower at a nuclear facility . US President Bush welcomes decision , but North Korea still has work to do . Bush says he 'll remove North Korea from list of state sponsors of terrorism .