North Korea has pledged to strengthen its nuclear weapons programme, after the UN Security Council voted to expand existing sanctions against Pyongyang.
China and the US held weeks of top-level negotiations over the international response before the resolution was submitted for a vote.
Al Jazeera's James Bays, reporting from the UN headquarters, said: "In the past there was opposition from China to any fresh action against North Korea.
"I think what changed things was the rocket launch in December, described as a "defiant step" by the international community."
Tough measures were sought by the US against North Korea's government, while China has sought to shield its trade ally against sanctions.
Even though the resolution does not impose new sanctions on Pyongyang, diplomats said China's support was a significant diplomatic blow to Pyongyang.
Six-party talks aimed at halting North Korea's nuclear programme have involved North Korea, the US, China, Japan, Russia and South Korea. They have been held intermittently since 2003, but stalled since 2008.
South Korea says the North is technically ready for a third nuclear test, and satellite images show it is actively working on its nuclear site.
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The United Nations imposed new sanctions on North Korea after a December rocket launch [Reuters]
Aljazeera