THE dark cloud of the menace of North Korea has proved to have a silver lining. Distrust of that country and its nuclear programme has been the catalyst for a dramatic improvement in Japan-South Korea relations and has played a part in prompting Washington's cautious efforts to mend ties with Beijing. It was not the only factor. After generations of suspicion, the Seoul-Tokyo relationship was ripe for repair. The election of reformist leaders in both countries allowed Japan to offer its deepest apology yet for its appalling treatment of Koreans duringWorld War II. But it is fear of North Korea that has Northeast Asia most on edge. And while Japan and South Korea move towards full reconciliation - and both are grateful for US President Bill Clinton's firm statement that an attack of South Korea would be considered an attack on the United States - none can ignore the need for support from Beijing. The knowledge that China alone carries some influence with Pyongyang - and that China's long border with North Korea makes it vital to the success of any international sanctions - has concentrated minds on both sides of the Pacific. It is premature to suggest that a good relationship with China is now the overwhelming priority of American foreign policy, or that Washington will sacrifice support for human rights and democracy for quick results with Beijing. China cannot count on automatic renewal of its Most Favoured Nation trading status or a cooling of US admiration for Chris Patten's attempts to broaden democracy in Hong Kong. The North Korean example, however, is one more reminder to Mr Clinton of China's importance as a world player. Improved US-China relations are vital to regional stability as well as for the resolution of bilateral issues.