Secretary of State John Kerry urged the world to show its resolve in the face of North Korea's nuclear provocations or risk emboldening Iran, which is under scrutiny over its uranium enrichment program.

In defiance of U.N. Security Council resolutions, the latest issued last month, North Korea on Tuesday detonated a nuclear device at a remote underground site. It is seen as a key step toward its goal of building a bomb small enough to be fitted on a missile capable of striking the United States. Iran, like North Korea, is also under stiff sanctions, and negotiations with the West over its nuclear program have similarly stalled.

The U.N. Security Council has issued three separate resolutions on North Korea, in response to its nuclear and missile tests since 2006. The latest resolution, which tightened sanctions, followed a December satellite launch that the U.S. says could serve to develop the North's ballistic missile capability.