After much pondering, I think I've finally realized one solid reason why some people are asking for UN approval before any military action against Iraq. Among the Bush administration's several caps on the hawkish hat rack, one reads "Defender of Universal Human Rights," while another reads "Liberator of Oppressed People and Exporter of Democracy." Now the US, being a particular, national government, can't really enforce universal rights anywhere than within its particular boundaries, nor can it replace an entire government the way it would replace a corrupt official within its own administration. Rather, that is the baliwick of local governments and people. Since, in the case of Iraq, the local government is none too respectful of personal dignity, some transnational body, like the UN, is the only body with anywhere close to the proper authority to impose such disciplinary measures, as a superior chastising a subordinate.
I'm not sure I believe it, but at least I think I understand it.