Defiant North Korea sets off nuclear explosion
South Korea North Korea
South Korean special police officers patrol with a bomb sniffing dog near the U.S. Embassy in Seoul, South Korea, Tuesday, Feb. 12, 2013. North Korea conducted a nuclear test at an underground site in the remote northeast Tuesday, taking an important step toward its goal of building a bomb small enough to be fitted on a missile that could reach United States. (AP Photo/Lee Jin-man)






