North Korea confirmed it conducted its biggest nuclear test yet earlier today and the action was quickly condemned by other countries, including China. The United Nations Security Council has scheduled an emergency meeting at 9 a.m. EST. President Obama issued a statement, "These provocations do not make North Korea more secure. Far from achieving its stated goal of becoming a strong and prosperous nation, North Korea has instead increasingly isolated and impoverished its people through its ill-advised pursuit of weapons of mass destruction and their means of delivery."

According to BBC News, "Seismic activity was then detected by monitoring agencies from several nations at 11:57 (02:57 GMT) on Tuesday. A shallow earthquake with a magnitude of 4.9 was recorded, the US Geological Survey said." The NY Times reports:

Early Tuesday morning in Washington the office of the director of national intelligence, James R. Clapper Jr., issued a statement suggesting the North Koreans were, on their third try, beginning to produce nuclear devices with substantial explosive power. “The explosion yield was approximately several kilotons,” the announcement said, which was less specific than a South Korean Defense Ministry estimate of six to seven kilotons. That would be far greater than the yield of less than one kiloton detected in the North’s 2006 test, but it is unclear how it would measure up to the last test, in 2009, which had estimated yield of two to six kilotons. By comparison, the first bomb the United States dropped on Japan, which devastated Hiroshima in 1945, had an explosive yield of 15 kilotons.

North Korea said in a statement, "This nuclear test was our preliminary measure, for which we exercised our most restraint. If the U.S. continues to be hostile until the end and complicates affairs, we cannot but consecutively take high-level secondary and third measures."

A North Korean analyst, Leonid Petrov, told Bloomberg News, "It just shows the failure of diplomacy and the continuation of the old broken-record story, the game of cat- and-mouse where North Korea is trying to intimidate its neighbors and the neighbors are trying to push for more deterrents and an escalation of tensions is inevitable."

China, which is North Korea's closest ally, said today, "The Democratic People's Republic of Korea, in spite of the international community's widespread opposition, once again carried out a nuclear test. The Chinese government expresses firm opposition."