On June 30, a temporary, appointed Iraqi government will assume what the Bush administration now calls "limited sovereignty” over a country still policed by troops under foreign command. The six-month period during which that interim caretaker government, outlined Wednesday at the United Nations Security Council by special envoy Lakhdar Brahimi, will have nominal control of Iraq may well prove to be the most precarious of the entire Iraqi venture. A weak government that lacks popular legitimacy will attempt to exercise authority over a restive country bristling with militias, all while picking its way through the minefield that will be its relationship with the United States.