North Korea is a country in East Asia, in the northern part of the Korean Peninsula. Pyongyang is both the nation's capital as well as its largest city, with a population just over 2.5 million. North Korea claims success in another powerfil nuclear test Friday morning, claiming to have successfully detonated a nuclear warhead that could be mounted on ballistic rockets. State media said the test would enable North Korea to produce "a variety of smaller, lighter and diversified nuclear warheads of higher strike power." "It's hard for us to verify their claim. My deep fear is that they will launch a live nuclear weapon on one of their missiles, but that would be extremely dangerous as that could trigger a war," said Melissa Hanham, a senior research associate at the James Martin Center for Nonproliferation Studies.