Economic lifelines from China and South Korea can keep the repressive regime afloat, even if every other country cuts North Korea off.

Surprisingly, communist China, North Korea's traditional ally, showed greater willingness to squeeze it than did America's ally, South Korea.

The North Korean nuclear test forced China's leaders to choose between North Korea and an international coalition led by the US. Their decision to stand with the world instead of with its communist little brother is the silver lining of the crisis and ultimately may be more significant than whatever the North Koreans do. In future years, people may point to the North Korean nuclear crisis as a turning point that brought China on the same side as the US and Japan instead of creating two hostile blocs in Asia.

To keep China on board, the Bush administration must convince Beijing along with Pyongyang of its good faith - that it uses sanctions to pull North Korea back to the negotiating table and not put a noose around its neck.

The conventional wisdom was that Beijing would never pressure North Korea for two reasons: it is more afraid of destabilising its neighbour and driving thousands of refugees across the border into northeast China - a region already troubled by massive unemployment and labour unrest - than it is of a North Korea armed with nuclear weapons, and it wants to prevent Korean reunification under a government led by Seoul that could place US armed forces right on China's border.

This time, however, China defied expectations. It voted "yes" on a muscular UN Security Council resolution that, while ruling out the use of force for the time being, is much stronger than anything China - a long-time opponent of sanctions especially in its own neighbourhood - has been willing to swallow in the past.

China's ambassador to the United Nations was misquoted by the press recently as saying China would not enforce inspections of North Korean freight as required by the resolution. But in fact, he only ruled out interdicting ships at sea, a dangerous mission that even gives the US military pause. Trucks carrying cargo from North Korea are now inspected at the Chinese border.

The Chinese government has gone beyond the resolution's requirements to order at least some banks to halt transactions with North Korea, a stern measure that devastates the nation's ability to conduct foreign trade. Chinese banking regulators have been queasy about handling money from North Korea ever since the US identified a bank in Macao, the former Portuguese colony now part of the People's Republic of China, as a conduit allegedly used by Pyongyang to launder counterfeit US dollars. Beijing has signalled a clear change in attitude.

Even before North Korea's nuclear blast, China had raised the price it charged Pyongyang for oil. If North Korea refuses to return to talks or tests again, China may close the pipeline temporarily as it did in 2003.

Meanwhile, China's propaganda authorities allow Chinese tabloids and Internet news sites to criticise North Korea's actions freely, a sure sign they are building popular support for a tough response.

China's own interests motivate the tough stance with its erstwhile ally: For one thing, China's pride is involved. North Korean leader Kim Jong-il violated minimum standards of the traditional friendship between the two communist countries last summer when he refused to meet with a high-level Chinese envoy sent to Pyongyang to discuss the missile tests, or with Mao Zedong's son during an annual visit to the grave of his brother killed during the 1950-53 Korean War.

Beijing sees the timing of the nuclear test - during the Chinese Communist Party's most important annual meeting, the day after the new Japanese prime minister visited President Hu Jintao, and just following its week-long National Day holiday - as a deliberate slap in the face. The government's statement following the test was the most sharply worded of any country's, reflecting genuine anger.

Moreover, China is more concerned about its own international reputation than it used to be. It took pride in the Six Party Talks, its unprecedented effort to mediate the conflict that Pyongyang now has spoiled.

Beijing seeks to show the world it is a responsible power by distancing itself from North Korea's roguish violation of international norms. China also has an interest in preserving the global non-proliferation regime, teetering on the brink of collapse, and not seeing its status as a member of the elite club of acknowledged nuclear powers diluted.

Although Americans may not yet recognise it, the newest and most important factor driving China's response is its relationship with Japan. China's highest foreign-policy priority in Asia is repairing its troubled relations with Japan, and the Chinese realise the North Korean crisis can help them do that.

A common enemy can unite even countries that don't like each other much.

Many of the Chinese political elite blame the dangerous deterioration of relations with Japan on former president Jiang Zemin, whose Patriotic Education Campaign had stirred historical memories of Japan's long occupation of China during the 1930s and 40s. Jiang's harping on history to senior officials, even the emperor, when he visited Japan in 1998 further estranged the Japanese public and its politicians.

Hu is eager to contrast his diplomatic skills with those of his predecessor. His administration worked out a pragmatic understanding with incoming prime minister Shinzo Abe to get relations back on track. China announced an "agreement to eliminate the political obstacle" while Abe remained publicly non-committal about whether he intended to visit Yasukuni. Abe made Beijing rather than Washington the destination of his first foreign trip. The diplomatic breakthrough was a triumph for Hu - until North Korea spoiled it.

Showing backbone against North Korea also discourages Tokyo from following Pyongyang down the nuclear path. From the Chinese perspective, a nuclear Japan is a nightmare more horrifying than a nuclear North Korea. The Japanese, directly threatened by North Korean missiles, are more likely to open the question if they see the Chinese passively accept North Korea's nuclear weapons.

The North Korean nuclear test, by driving China to become part of the solution and averting conflict between China and Japan, shifted strategic ground in Northeast Asia. Paradoxically, it may have made Northeast Asia less dangerous, not more so.

Susan L Shirk is professor in the Graduate School of International Relations and Pacific Studies, the University of California at San Diego and director of the UC Institute on Global Conflict and Cooperation. She is author of the forthcoming book "China: Fragile Superpower" and was deputy assistant secretary of state for China, 1997 to 2000.

Susan L Shirk

YaleGlobal

San Diego

Copyright: Yale Centre for the Study of Globalization.