PYONGYANG, North Korea (AP) - North Korea says it has tested a "miniaturised" nuclear device in defiance of U.N. orders to stop building atomic weapons.
Official state media reported on Tuesday that it was conducted in a safe manner.
This third nuclear test could take North Korea closer to its goal of building a nuclear warhead small enough to be mounted on a long-range missile.
Any test would be seen as another big step toward North Korea's goal of building a warhead that can be mounted on a missile. It would also be a bold signal from young leader Kim Jong Un, who took power in December 2011 following the death of his father, Kim Jong Il.
A nuclear test would also be a challenge to the U.N. Security Council, which recently punished Pyongyang for launching a long-range rocket seen as a covert test of ballistic missile technology. In condemning that December rocket launch and imposing more sanctions on Pyongyang, the council had demanded a stop to future launches and ordered North Korea to respect a ban on nuclear activity - or face "significant action" by the U.N.
In Washington, the White House had no immediate comment on Tuesday's developments.