The Ryanggang explosion was a large explosion that took place in North Korea on 9 September 2004 in the northern province of Ryanggang. The nature and cause of the suspected explosion is the subject of speculation. No neighboring nations have claimed any detection of radioactive isotopes characteristic of a nuclear explosion. The suspected explosion The suspected explosion occurred near Wŏltan Workers' District (Wŏltal-lodongjagu) (41°19'47"N 127°05'02"E) in the county of Kimhyŏngjik in Ryanggang Province, a mountainous region, about above sea level. The explosion was about from the border with China. The area contains several military installations, including the Yeongjeo-dong ballistic missile base. Early reports stated that seismic activity had been detected early on 9 September 2004, and this was correlated with a "strangely shaped cloud", suspected to be a mushroom cloud. Together these would indicate a large explosion. The date, 9 September 2004, the 56th anniversary of the formation of North Korea, was taken as significant because North Korea has a history of making grand military gestures on significant dates. However, the original reports have been contradicted by later reports denying that there was any explosion. Reaction The incident was not reported internationally until 12 September 2004, when the South Korean news agency Yonhap cited a source in Beijing, China, which said a mushroom cloud had been observed. In addition, suspicion was raised by the fact that there was no mention of the explosion on internal North Korean media. However, North Korean news is usually a method employed by governing figures to make the ruling party's decisions more favourable to the people (national and internationally); therefore, unfavourable stories are commonly not broadcast. The Ryongchon disaster earlier in 2004 was reported only several days after the event. There was immediate popular speculation that the explosion was nuclear in origin. United States Secretary of State Colin Powell said there was "no indication" that it was nuclear, and South Korea similarly said that it did not appear to be nuclear. It would be some days before the effects of a nuclear explosion would be unequivocally visible to apolitical authorities. It would not be possible to hide the nuclear nature of such an explosion for long, as the radioactive isotopes created by a nuclear explosion would be detectable to outside observers around the world. From North Korea North Korea initially denied that the explosion was nuclear. When prompted for an explanation, North Korea's foreign minister,