UPDATE/North Korea says it has tested a "miniaturized" nuclear device in defiance of U.N. orders to stop building atomic weapons.
Official state media reported 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.
PYONGYANG, North Korea (AP) - North Korea says it has successfully conducted third underground nuclear test.
SEOUL, South Korea (AP) - South Korea says it suspects a nuclear test caused an earthquake Tuesday in North Korea just north of a site where the country conducted two previous atomic tests. North Korea has yet to confirm whether the tremor resulted from a widely anticipated third nuclear test.
A U.N. nuclear test monitoring organization says it detected what it's calling an "unusual seismic event" in North Korea.
One South Korean earthquake specialist says "there is a high possibility that North Korea has conducted a nuclear test." He says a magnitude 3.9 earthquake and a magnitude 4.5 quake were detected in the North's 2006 and 2009 nuclear tests.
Earlier Tuesday, North Korea's powerful politburo vowed to continue firing "powerful long-range rockets," but a statement by state media made no mention of a nuclear test.
Last month, North Korea's National Defense Commission said the United States was its prime target for a nuclear test and long-range rocket launches.