Lee Jin-Man/Associated Press
PYONGYANG, North Korea -- North Korea says its nuclear test was its "first response" to U.S. threats and warns it will continue with unspecified "second and third measures of greater intensity" if the United States maintains its hostility.
The White House is calling the test a "highly provocative act" that threatens U.S. security and international peace. In a statement issued early Tuesday, President Barack Obama promises to "continue to take steps necessary to defend ourselves and our allies."
He also urges "swift and credible action by the international community." The North's Foreign Ministry said in a statement that its nuclear test Tuesday was a "self-defensive measure" that does not violate any international law.
The test is seen as a crucial step toward North Korea's goal of building a bomb small enough to be fitted on a missile capable of striking the United States. North Korea's test drew immediate condemnation from Washington, the U.N. and others.
Even its only major ally, China, voiced opposition.