US President Barack Obama said North Korea's latest nuclear test was a "highly provocative act" that hurt stability in the region and called its nuclear program a threat to U.S. and international security.
"The danger posed by North Korea's threatening activities warrants further swift and credible action by the international community. The United States will also continue to take steps necessary to defend ourselves and our allies," Obama said in a statement.
"We will strengthen close coordination with allies and partners and work with our Six-Party partners, the United Nations Security Council, and other UN member states to pursue firm action," he said.