HONG KONG Since the nuclear test in North Korea, there have been scores of suggestions on what to do about it. But few have started with the fundamental question: Why did the North explode the device?  Only by having a better idea of Pyongyang's goals can we fashion a realistic response.  Six years of bluster and insults from Washington have done nothing to deter Kim Jong Il. More likely they have only made him more certain of the righteousness of his efforts, to the point of being prepared to anger China.  Anyone who has been to North Korea must come away with a sense of a nationalism encountered nowhere else on the planet. Hostility to the United States, aerial destroyer of much of urban North Korea, is the most paraded; Japan, occupier from 1910 to 1945, is not far behind.  But do not imagine that China and Russia provide the nation with friends. Their help is acknowledged, but grudgingly and with the suggestion that it is not "sincere" (a similar defensive nationalism is evident among many South Koreans in relation to the United States).  Extreme nationalism is fostered by a Pyongyang regime with nothing else to offer. But it is also part of the psyche of a small nation that has survived against the odds for millennia. Given their border with China they are even more acutely aware than their southern brethren of the large population of ethnic Koreans across the border, and of China's attempts to treat Korean history as part of its own.  Even if there were no diplomatic gains to be had, Kim probably thinks that the bomb has assured him of a place in the pantheon of Korean heroes.  The dream of uniting in the name of Kim, father and son, can longer be contemplated. But the bomb, symbol of Koreans defying their enemies and the whole world, is there for eternity. Even some in South Korea feel that awful though he is, Kim has done something for the nation. Perhaps they resent the fact that it was the North which built a bomb, not the outward-looking, prosperous South.  To the extent that psychology rather than diplomatic calculation played a major part in the decision and its timing, a correct response is all the harder to find. But one must at least acknowledge what is in Kim's mind.  The second factor is this: North Korea cares far more about the United States than it does about China. The six-party talks have provided a fig leaf whereby the U.S. can engage to a minor extent with Pyongyang, but the North wants much more in return for concessions over arms.  The South's "sunshine policy" is useful to the North not only for the few economic benefits it has brought, but also because it has acted as a wedge between Seoul and Washington.  Pyongyang makes a virtue out of self-inflicted suffering. With or without communism, Kim sees himself as the personification of stubborn Korean pride, holding firm even as China goes down the capitalist road and the South sells out to the West and Japan.  Yes, the North Korean regime uses nationalism to protect itself and its privileges. Yes, it is genuinely fearful of the efforts of the United States and some in South Korea to engineer regime change. Yes, it feels the need for a nuclear weapon as a last-gasp defense, and because its conventional forces are technologically backward.  But above all it wants respect, to be treated as normal, as an equal, by the United States. It knows that China, never one to desert old allies and itself fearful of regime disintegration, will not push it too far. Ditto South Korea.  It knows that economic sanctions will do little more than make a bad economy worse - and may not even counteract the benefits to the North of high prices for its ore exports.  The United States may be the No. 1 enemy, but its recognition, even friendship, is the No. 1 goal.  It may be immoral to deal with such an oppressive, extremist and abnormal regime, which has starved its own people.  But if the greater U.S. goal is to control strategic weapons, and not regime change, then Washington probably does have immense leverage - if it is prepared to give Pyongyang the self-respect it craves. That is especially so as Kim has now played his main card and, presumably, has assuaged his own ego.  The United States is not only the most powerful nation on earth; it is the only one in the six-party talks which does not share land or sea borders with the North, and whose enmity derives from a global divide which no longer exists.  Kim will probably not formally give up his bomb in return for a peace treaty, but he could be persuaded to stop making more.