The resolution, which was drafted by the United States and China, was passed 15-0 in a speedy vote hours after North Korea threatened for the first time to launch a pre-emptive nuclear strike against the United States and South Korea.
"The strength, breadth and severity of these sanctions will raise the cost to North Korea of its illicit nuclear program," the U.S. ambassador to the United Nations, Susan E. Rice, told reporters after the vote. "Taken together, these sanctions will bite and bite hard."
Li Baodong, the ambassador from China, whose support for the new sanctions angered the North Korean government, told reporters the resolution was aimed at the long-term goal of denuclearizing the Korean Peninsula.
"This resolution is a very important step," he told reporters. Li called passage of the resolution "a reflection of the view and determination of the international community."
The resolution, which was drafted three weeks after the Feb. 12 underground test by North Korea, is the Security Council's fourth against the reclusive North Korean government. It contains new restrictions that will block financial transactions, limit North Korea's reliance on bulk transfers of cash, further empower other countries to inspect suspicious North Korean cargo, and expand a blacklist of items that the country is prohibited from importing. The sanctions also place new constraints on North Korean diplomats, raising their risk of expulsion from host countries.
Asked if she thought the sanctions would break the pattern of North Korean defiance of earlier punishments imposed by the Security Council, Rice said: "The choice lies with the decision that the North Korean leadership makes."
She dismissed the North's vows of a pre-emptive nuclear strike, saying "North Korea will achieve nothing by continued threats and provocations."
In recent days, with the resolution set to pass, North Korea characterized the sanctions as part of an "act of war" in its escalating invective against the United States and its allies. Earlier this week it declared the 1953 armistice that stopped the Korean War null and void and threatened to turn Washington and Seoul into "a sea in flames" with "lighter and smaller nukes."
The combative country has often warned that it has the right to launch pre-emptive military strikes against the United States, claiming that the western power wants to start a war on the Korean Peninsula. But on Thursday the North ratcheted up the hostile language by talking about pre-emptive nuclear strikes for the first time, citing the continuing joint U.S.-South Korean military exercises as proof that the United States and its allies were preparing for "a nuclear war aimed to mount a pre-emptive strike" on North Korea.
"Now that the U.S. is set to light a fuse for a nuclear war, the revolutionary armed forces of the DPRK will exercise the right to a pre-emptive nuclear attack to destroy the strongholds of the aggressors and to defend the supreme interests of the country," a spokesman of the North Korean Foreign Ministry said in a Korean-language statement carried by the North's official Korean Central News Agency. He used the acronym for his country's official name, Democratic People's Republic of Korea.
The spokesman said that North Korea was no longer bound by the 1953 armistice ending the Korean War - and its military was free to "take military actions for self-defense against any target any moment" starting from Monday, when it declared the cease-fire was terminated.
The resolution the United Nations adopted to impose more sanctions against the North "will compel the DPRK to take at an earlier date more powerful second and third countermeasures as it had declared," the spokesman added, without elaborating.
In the past, whenever the United Nations considered more sanctions, North Korea's typically strident rhetoric had grown harsher with threats of war. The threats were just that, and analysts said the message was meant as much for its home population, to whom they said the young leader Kim Jong Un sought to inspire a sense of crisis, as it was meant to unsettle the region to force Washington to engage it with concessions.
Photos filed by news agencies from the North Korean capital, Pyongyang, and carried in South Korean media Thursday showed buses covered with military camouflage and university students rushing out of their classroom building in military uniforms in a military exercise.
Few analysts believe that North Korea would launch a military attack at the United States, a decision that would be suicidal for the regime. But officials in Seoul feared that North Korea might attempt an armed skirmish to test the military resolve of Park Geun-hye, South Korea's first female president, who took office less than two weeks ago.