SEOUL Since the UN Security Council ordered sanctions against North Korea, Seoul has done its share of tough talking, and it will probably support the embargo once it is imposed. But it is unlikely that South Korea will maintain pressure on the North for long.  More likely, South Korea will use the first available excuse to walk away from the sanctions, citing, for example, humanitarian concerns (i.e. a major flood in North Korea). Already now, South Korean diplomats are working hard to make sure that the sanctions will not be too harsh, and they will probably find some support from China and Russia.  The first signs of such an attitude are already present: On Sunday, a South Korean government official said that the UN Security Council's unanimous adoption of the sanctions is "irrelevant to inter-Korean business," essentially confirming Seoul's willingness to continue unilateral aid to the North (most "inter-Korean businesses" are money-loosing enterprises paid for by South Korean taxpayers).  This might appear strange: after all, South Korea would seem to be the country most threatened by North Korean nuclear weapons. Some Americans blame South Korean indecisiveness on the nationalist left which now dominates Seoul's politics. The major reason for Seoul's attitude, however, is not an inability to grasp the seriousness of the situation, but rather a very real divergence of interests with Washington.  For Washington, the North Korean decision to go nuclear is dangerous, above all, because it creates a precedent of nuclear proliferation.  When viewed from the more limited perspective of Seoul, nuclear proliferation is worrisome, but not a direct concern. None of those rogue nuclear-armed states which might eventually arise in, say, the Middle East or Africa is likely to target Seoul.  At the same time, South Korea is not particularly afraid of a North Korean attack. South Koreans assume (perhaps correctly) that Pyongyang's goal is the survival of the Kim regime, and that the nuclear weapons are designed as a negotiating chip and a deterrent. South Koreans further assume that North Korean leaders know how slim Pyongyang's chances are of winning a real war, and therefore they will not start any large- scale violence unless feel completely cornered. Hence the South would shrink away from any actions which might destabilize or provoke North Korea - such as truly efficient sanctions.  It is also worth noting that nuclear weapons do not substantially increase the level of threat to the average South Korean. Half of the South's population, some 23 million people, lives in the Seoul metropolitan area, which is located within range of several thousand North Korean guns. In effect, North Korean artillery positions are right in the northern suburbs of the South Korean capital, and in the case of war an artillery barrage could kill tens of thousands before the batteries are silenced. One or two small and unreliable nuclear devices do not alter the balance of death too much.  Even if international pressure does not provoke a war but instead brings about the collapse of the Kim regime, that would not necessarily be good news to the average South Korean. People in Seoul are terrified by the thought of the tremendous costs of rebuilding the destitute North. The long-term goal of Seoul is the gradual evolution of North Korea, during which the income gap would narrow.  Hence if sanctions are tough enough to have a serious effect, they might either provoke a war or an internal collapse, and neither is in South Korea's interest. So in all probability, we will see Seoul joining the sanction game for a while, only to withdraw at the first opportunity. Andrei Lankov is a Korean affairs specialist at the Australian National University, Canberra.