The collaboration between us intelligence agencies and UN arms inspectors in Iraq is disturbing, but hardly surprising. It's disturbing because, if the UN is perceived as serving the purposes of a particular country, its credibility is weakened. Impartiality is vital. In the past, some UN peacekeeping and observer missions - from Korea to the Congo to the Middle East - were criticized for serving the policies of one nation or alliance. Such criticism was endemic during the cold-war. But a clear-cut case of a mission becoming a tool of a national government? The situation in Iraq during the two years prior to last December's pullout of the UN Special Commission there came uncomfortably close to that description. What began with a request from UNSCOM's former director, Rolf Ekeus, for increased US technological help in penetrating the Iraqis' labrynthine system for concealing weapons grew into a dubious synergy. Under Ekeus's successor, Australian Richard Butler, US intelligence reportedly used the UN weapons inspection team as a cover for installing a supersensitive listening device to intercept high-level Iraqi communications and beam them to a US satellite. Mr. Butler has firmly denied that his commission was ever engaged in spying. All that UNSCOM did, he affirms, was in accord with its mission of ferreting out and destroying Iraq's weapons of mass destruction. It's just that key data collected in that effort came through the application of US surveillance technology and went through US analysts. The cooperation between UNSCOM and US intelligence was not surprising, given their convergent goals. The US, clearly, could give weapons inspectors capabilities they couldn't get elsewhere. Other countries, too, contributed personnel and intelligence know-how. Saddam gets at least a propaganda assist from all this. It lends credence to his accusations of US spying. But UN inspectors had to use every resource available to counter Saddam's determination to thwart their work. That work has now halted. More bombs have fallen; Iraq is irate; and dissension is loud on the UN Security Council. But the job of keeping mass destruction weapons out of the hands of a government likely to use them still must be done. It's best undertaken by the international community, not the US alone. Washington must try to salvage the UN weapons-inspection mission to slow Saddam's weapons program. That effort doesn't mesh easily with the US goal of removing Saddam from office. But it should be made nonetheless.