On October 9, 2006, North Korea claimed to have detonated a nuclear device deep underground <ref>http://news.bbc.co.uk/2/hi/asia-pacific/6032525.stm</ref> but the yield was equivelent to only approximately 400 tons of chemical high explosive and some analysts believe no chain reaction was achieved. | On October 9, 2006, North Korea claimed to have detonated a nuclear device deep underground <ref>http://news.bbc.co.uk/2/hi/asia-pacific/6032525.stm</ref> but the yield was equivelent to only approximately 400 tons of chemical high explosive and some analysts believe no chain reaction was achieved. |