"Iraq's chemical, biological, and nuclear weapons programs, together with Iraqi long-range missile development and support for al-Queda terrorism, were the primary justifications put forward for military action. On March 17, 2003, President Bush issued an ultimatum demanding that Saddam Hussein and his sons depart from Iraq within 48 hours. On March 19, offensive operations began with air strikes against Iraqi leadership positions. By April 15, after 27 days of operations, coalition forces were in relative control of all major Iraqi cities and Iraqi political and military leadership had disintegrated. On May 1, 2003, President Bush declared an end to major combat operations. There was no use of chemical or biological (CB) weapons, and no CB or nuclear weapons stockpiles or production facilities have been found. The major challenges to coalition forces are now quelling a persistent Iraqi resistance movement, restoring civil order, and providing basic services to the urban population. U.S. troops continue to come under increasingly frequent attacks. Though initially denying that these attacks were the work of an organized resistance movement, DOD officials have now acknowledged there is regional/local organization, with apparently ample supplies of arms and funding."
CRS Report for Congress, RL31701
U.S. Dept. of State, Foreign Press Centers: http://www.fpc.state.gov/