The U.N. itself has proven the laughability of the notion that it is a serious international body with the ability to create and sustain a government in such a volatile place.
The U.S. would defeat its own purpose if it liberated Iraq only to turn it over to the U.N. - the U.N. can't even stand up under its own power!
The UN is a joke. Let the Iraqis figure out what they want.
Another matter is our State Department. They've done a fine job too. Remember the last ambassador to Iraq actually told Saddam that the US would have no interest in a dispute between Iraq and Kuwait. That was in late July 1990.