Satellite images of North Korea 's Yongbyon nuclear facility have again raised questions about whether the country has restarted its plutonium production reactor -- regarded by western experts as a key component in the development of a nuclear weapon . Researchers from U.S.-based groups examined satellite images from August 31 . They showed two columns of steam rising from a building , believed to house the reactor 's steam turbines and electric generators . The steam indicates that the reactor is in or nearing operation , wrote Nick Hansen and Jeffrey Lewis , in a 38 North blog post , a program of the U.S.-Korea Institute at SAIS . Work to reopen the reactor progressed throughout this spring and summer , they wrote . `` This is something they ( North Koreans ) very much need to arm their arsenal , and that is really linked into what they see as marketing power on the international plane , '' Jasper Kim , founder of Asia-Pacific Global Research Group , told CNN . `` Without this type of nuclear capability , or at least the perception of the threat of having nuclear capabilities , North Korea really has few bargaining chips . '' But Pyongyang has gone down this path before . First completed in the 1980s , North Korea agreed to shut the Yongbyon facility in 1994 after backing down from a threat to withdraw from the nuclear nonproliferation treaty . It restarted the reactor in 2002 , before it was once again disabled in 2007 after a six-party agreement between China , the United States , North and South Korea , Japan and Russia . In April this year , North Korea stated that it would be `` readjusting and restarting all the nuclear facilities '' in Yongbyon , which includes the uranium enrichment plant and the reactor , the country 's state-run news agency KCNA said . `` This work will be put into practice without delay , '' the North Korean report stated at the time . Analysts say it appears North Korea has fulfilled its word . David Albright and Robert Avagyan , from the Institute for Science and International Security , examined the latest satellite images and agreed the venting appeared most likely connected to the operation of the reactor . They also wrote last month that North Korea appeared to have greatly expanded a building used in the uranium enrichment process . The expansions and developments `` provide North Korea with the ability to expand its stocks of plutonium , as well as produce more highly enriched uranium for nuclear weapons , '' wrote Albright and Avagyan . They estimated that North Korea would likely need two to three years to produce plutonium , which is essential in creating nuclear weapons . `` There remains time to negotiate a shutdown of the reactor before North Korea can use any of this new plutonium in nuclear weapons '' they added . `` If a shutdown is achieved in the next six months , the reactor would have produced very little plutonium . ''
Researchers point to steam at North Korean facility . They write that it 's a sign that the reactor is near or in operation . Comment: North Korea said in April it would restart nuclear facility in April .