North Korea's blast was similar to previous nuclear tests, the Vienna-based monitoring agency CTBTO said early Tuesday, slamming it as a potential threat to international security. If confirmed as a nuclear test, it would represent "a clear threat to international peace and security...," the agency added in a statement. "The event shows explosion-like characteristics and its location is roughly congruent with the 2006 and 2009 DPRK (Democratic People's Republic of Korea) nuclear tests," the agency said.

North Korea's blast was similar to previous nuclear tests, the Vienna-based monitoring agency CTBTO said early Tuesday, slamming it as a potential threat to international security. "The event shows explosion-like characteristics and its location is roughly congruent with the 2006 and 2009 DPRK (Democratic People's Republic of Korea) nuclear tests," agency chief Tibor Toth said in a statement. "For now, further data and analysis are necessary to establish what kind of event this is," he added.