North Korea conducts third controversial nuclear test

PYONGYANG, North Korea (AP) - Defying UN warnings, North Korea on Tuesday conducted its third nuclear test in the remote, snowy north-east, taking a crucial step toward its goal of building a bomb small enough to be fitted on a missile capable of striking the United States.

North Korea said its third atomic test was merely its "first response" to what it called US threats, and said it will continue with unspecified "second and third measures of greater intensity" if Washington maintains its hostility.

The underground test, which set off powerful seismic waves, drew immediate condemnation from Washington, the UN and others. Even its only major ally, China, voiced opposition.

US President Barack Obama, who was scheduled to give a State of the Union address later Tuesday, said nuclear tests "do not make North Korea more secure." Instead, North Korea has "increasingly isolated and impoverished its people through its ill-advised pursuit of weapons of mass destruction," he said in a statement.