The UN Security Council voted unanimously to impose financial and weapons sanctions on North Korea for its claimed nuclear test in a resolution that Pyongyang's envoy swiftly rejected as "gangster-like".
Japanese Prime Minister Shinzo Abe immediately said Tokyo would consider further punitive steps against the reclusive communist state, while a top Russian envoy arrived in Seoul on Sunday to discuss his trip to Pyongyang last week.
US Secretary of State Condoleezza Rice was also set to visit Japan, South Korea and China later in the week to discuss enforcing the provisions in the US-drafted resolution.
The resolution, which called Pyongyang's action a "clear threat to international peace and security", allows nations to stop cargo going to and from North Korea to check for weapons of mass destruction or related supplies.
The resolution bars trade with North Korea in dangerous weapons. It also imposes bans on heavy conventional weapons and luxury goods and asks nations to freeze funds connected with North Korea's non-conventional arms programmes.
North Korea's UN ambassador, Pak Gil Yon, walked out of Saturday's Security Council meeting after accusing members of "gangster-like" action and warning that Pyongyang considered any further US pressure a "declaration of war".
North Korea has issued similar statements before, but this time it was before a formal audience.
US President George W. Bush said the resolution showed "the world is united in our opposition to its nuclear weapons plans" and Japan's Foreign Minister Taro Aso said North Korea had to "take concrete measures to resolve the issue".
Enforcement will depend largely on whether those who have traded with North Korea honour the bans, which now also have the support of China, the North's closest ally, as well as Russia.
"The key will be China sealing its border to prevent military/nuclear-related shipments in either direction," Ralph Cossa, president of Hawaii-based think tank CSIS Pacific Forum, said in an email commentary.