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 was to arrive in Seoul on Sunday for talks.
U.S 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 impose 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 the 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 militarynuclear-related shipments in either direction," Ralph Cossa, president of Hawaii-based think tank CSIS Pacific Forum, said in an email commentary.
ULTIMATUM FOR RESPONSE?
Most of Pyongyang's trade crosses through China, which fears a flood of refugees if the Pyongyang government collapses. North Korea also rests between China's border and South Korea, where 25,000 US troops are stationed.
In Seoul, the South Korean Foreign Ministry said on Sunday that it would "faithfully implement" the resolution. But South Korea has said it would not pull the plug on its two main projects in the North -- an industrial park and a mountain resort -- that supply a steady stream of cash to Pyongayng's leaders.
In Tokyo, Shoichi Nakagawa, chairman of the ruling Liberal Democratic Party (LDP)'s Policy Research Council, said Japan will adhere to its policy of not arming itself with nuclear weapons in response, but added that a debate on the issue was necessary.
China warned the 15 Security Council members not to provoke Pyongyang with "provocative steps," in particular inspections of cargo ships going to and from North Korea to check for weapons.
The provision was toned down at China's request, but still authorises countries to inspect cargo, putting an international imprimatur on the US-led Proliferation Security Initiative.
Begun in May 2003, the PSI encourages countries to interdict weapons from states of concern such as North Korea and Iran.
"China strongly urges the countries concerned to adopt a prudent and responsible attitude in this regard and refrain from taking any provocative steps that may intensify the tensions," its UN ambassador, Wang Guangya, said.
Japan, which last week imposed tough sanctions on North Korea including a six-month import ban, is likely to take fresh steps including a ban on luxury exports to the North, media reports said.
Tokyo will also study how it can cooperate with the controversial cargo inspections within the scope of its pacifist constitution, Aso said in several TV interviews on Sunday.
Some analysts said the threat of ship inspections was an ultimatum to North Korea to respond to diplomatic overtures and return to moribund six-party talks on its nuclear programmes.
"The ball is in North Korea's court. This is the last chance for them to show a positive response," Satoshi Morimoto, professor at Takushoku University.
North Korea has boycotted the talks with the South, the United States, China, Japan and Russia since last year because of a US crackdown on firms it suspects of aiding Pyongyang in illicit activities such as counterfeiting.
Russian Deputy Foreign Minister Alexander Alexeyev told reporters in Beijing after talks in Pyongyang that North Korea was ready to return to the six party talks but he expressed "cautious pessimism" about their revival.
He was due in Seoul later on Sunday.
There has been little official comment from North Korea, but on Sunday a 13-page ode to Kim il-Sung carried by KCNA said the country should not be judged on nuclear weapons alone.
"People of the world, do not measure our strong national power only by our possession of a satellite. Chosun (Korea) is the only country with the unity of a determined mind, which cannot be affected by a nuclear weapon or missile."