[4] The United States believed that Kangson has an output double that of Yongbyon Nuclear Scientific Research Center, though some analysts say it may be only 20 percent larger.
[4][5] In 2020 Olli Heinonen, formerly Deputy Director-General for Safeguards at the International Atomic Energy Agency, raised doubts about the building being an enrichment site.
[6] In 2021, Siegfried S. Hecker, former director of the Los Alamos National Laboratory who has visited North Korea nuclear facilities many times on behalf of the U.S., also stated that he was not convinced that Kangson was an enrichment site.
[4] The United States intelligence community began observing construction at the site in 2007, and identified it as an enrichment facility in 2010.
[5][9] In IAEA reports on North Korea in 2020, it was described that there are a group of buildings observation appear to be a uranium enrichment facility, and regular vehicle movements at the site suggest that activities are ongoing.