The United States has begun consultations with its allies in a bid to establish facts about North Korea's claim that it had conducted a new nuclear test, a State Department official said late Sunday.
"We are aware of the reports of a nuclear test by North Korea," the official told reporters on condition of anonymity. "We are consulting with our allies. Once we have established the facts, we will have more to say."
The comments came after North Korea said it had staged a "successful" underground nuclear test Monday, which was more powerful than its previous test.
South Korean officials said a tremor was detected around the northeastern town of Kilju, near where the first test was conducted in October 2006.