Updated 3:55 p.m. ET
UNITED NATIONSThe U.N. Security Council is strongly condemning North Korea's nuclear test and pledging further action.
A press statement approved by all 15 council members at an emergency meeting Tuesday morning says the test poses "a clear threat to international peace and security."
The council points out that in a resolution it approved unanimously last month stepping up sanctions for North Korea's missile test in December it promised to take "significant action" in the event of a new nuclear test.
"In line with this commitment and the gravity of this violation, the members of the Security Council will begin work immediately on appropriate measures in a Security Council resolution," the council says.
After the meeting, U.S. Ambassador to the U.N. Susan Rice told CBS News foreign affairs analyst Pamela Falk: "As you may anticipate, we and others have a number of further measures that we will be discussing with Council members in various spheres that will not only tighten the existing measures but augment the sanctions regime that is already quite strong as implemented in (UN Security Council Resolutions)1874 and 2087."
U.N. Secretary-General Ban Ki-moon welcomed the council statement and said he was encouraged by "the swift and overwhelming international condemnation of this wanton act."
Ban, a former South Korean foreign minister, expressed regret that his repeated appeals to North Korea's new young leader, Kim Jong Un, to give up its pursuit of nuclear weapons and address international concerns through dialogue "have fallen on deaf ears."
North Korea is the only country to carry out nuclear tests in the 21st century, he said, and the latest test in defiance of the U.N. and the international community "is a serious challenge to global efforts to curb nuclear proliferation."
Ban said he is also "profoundly concerned about the negative impact of this act on regional stability."
Even traditional allies for North Korea, Russia and China, have reacted harshly to the nuclear test, which was confirmed by U.S. intelligence Tuesday morning.
China expressed "firm opposition" Tuesday, as the reclusive nation's only other major ally, Russia, said it "decisively condemned" the move.
The statement from China's Foreign Ministry reflected Beijing's growing frustration with its communist neighbor's provocative behavior. But with Beijing stopping short of a condemnation, it also demonstrated China's reluctance to impose more severe measures that could destabilize the North's hardline regime.
China instead renewed its call for new denuclearization talks, and beseeched all parties to remain calm, and not take any further measure that could heighten tensions.
Russia took a stronger stance Tuesday, with the Interfax news agency quoting a Foreign Ministry source as saying Kremlin leaders "condemn these actions by North Korea and view them together with the ballistic rocket launch carried out earlier as a violation of the corresponding U.N. Security Council resolution."
President Barack Obama reacted sharply to the nuclear test Tuesday, promising swift international action to bring the rogue communist regime in line. The detonation came hours before the American leader's State of the Union address, where he was expected to address U.S. denuclearization plans.
In a statement, Obama called Pyongyang's third nuclear test in seven years a "highly provocative act" that threatens U.S. security and international peace. The reaction from the White House was significantly stronger than after North Korea's long-range missile test in December, when the administration only promised "appropriate action" alongside America's allies.
"The danger posed by North Korea's threatening activities warrants further swift and credible action by the international community," Obama said in a statement early Tuesday. "The United States will also continue to take steps necessary to defend ourselves and our allies."