Continued from page 1

“I don’t predict what North Korea will do, as a rule,” Mr. Snyder said. “But I have noticed that usually they have a high degree of consistency in terms of follow-through on this sort of expression of intent.”

If North Korea does conduct a nuclear test, governments and analysts will pay close attention to determine whether uranium was used. It is unclear whether North Korea has mastered the technology to produce highly enriched uranium and has enough for a bomb.

North Korea’s past two nuclear tests — in 2006 and 2009 in response to U.N. sanctions punishing it for launching rockets — were plutonium-based devices.

North Korea’s pursuit of its nuclear ambitions has strained its relationship with its ally China, and curtailed Beijing’s influence in Pyongyang.

China voted in support of the U.N. resolution that demanded Pyongyang abandon its nuclear weapons program in a “complete, verifiable and irreversible manner.” The resolution also ordered Pyongyang to cease rocket launches.

The Chinese supported the U.N. resolution because “they recognized that they have limited ability to restrain North Korea from taking additional actions that would have proved embarrassing to China,” said Mr. Snyder.

The National Defense Commission statement followed a warning from North Korea’s Foreign Ministry on Wednesday that Pyongyang will “take steps for physical counteraction to bolster the military capabilities for self-defense, including the nuclear deterrence, both qualitatively and quantitatively.”

White House spokesman Jay Carney said North Korea’s statement was “needlessly provocative” and a nuclear test would be a “significant violation of United Nations Security Council resolutions.”