[4] In the ensuing 2003-11 Iraq War, the Multi-National Force (MNF–I) led by the United States helped to establish a Shia-dominated federal government, which was soon opposed by an Iraqi insurgency.
[1] The main rationale given by the United States for its invasion of Iraq was based on allegations by the American and British governments that Saddam Hussein was developing weapons of mass destruction and that he thus presented a threat to his neighbors and to the world.
The resolution strengthened the mandate of the UN Monitoring and Verification Commission (UNMOVIC) and the International Atomic Energy Agency (IAEA), giving them authority to go anywhere, at any time and talk to anyone in order to verify Iraq's disarmament.
"[7] Throughout the early 2000s, the administrations of George W. Bush and Tony Blair worked to build a case for invading Iraq, culminating in the U.S. Secretary of State Colin Powell's address to the Security Council one month before the invasion.
The U.S. led the effort for "the redirection of former Iraqi weapons of mass destruction (WMD) scientists, technicians and engineers to civilian employment and discourage emigration of this community from Iraq.
The invasion phase consisted primarily of a conventionally fought war which included the capture of the Iraqi capital of Baghdad by American forces with the assistance of the United Kingdom, Australia and Poland.
While the special forces launched an amphibious assault from the Persian Gulf to secure Basra and the surrounding petroleum fields, the main invasion army moved into southern Iraq, occupying the region and engaging in the Battle of Nasiriyah on 23 March.
Massive air strikes across the country and against Iraqi command and control threw the defending army into chaos and prevented an effective resistance.
Invading U.S.-led forces were unable to immediately fill the power vacuum caused by the sudden collapse of a highly centralized state authority, resulting in weeks of virtual anarchy.
Another cause of resentment was the lack of immediate humanitarian aid and reconstruction efforts for Iraqis suffering from the invasion, the long-term effects of the repression and mismanagement of the Saddam Hussein regime, and international sanctions.
[18] The de-Ba'athification Commission set up by the Coalition Provisional Authority, the nature of selection of the Governing Council, and other policy decisions were interpreted by Sunni Arabs as actions intended to single out their community for discrimination; this encouraged the beginnings of sectarian tensions.
However, many lost their jobs and pensions with the disbanding of the Iraqi army by Paul Bremer; this, and the unwillingness of the Coalition Provisional Authority to negotiate with former Ba'ath elements, provided impetus for the initial insurgency.
Many young men without jobs or prospects and who had lost faith with the promises of the U.S. began to become drawn to Shiite Islamism, especially of the brand advocated by the cleric Muqtada al-Sadr.
Sadr's distinguished family background, and his fiery anti-occupation rhetoric and calls for the implementation of Islamic law, caused him to emerge as the leader of this portion of Iraqi Shiite society.
In June 2003, after being rejected from a spot on the Iraqi Governing Council, he had created a militia known as the Mahdi Army, whose mission he said was to help keep order and cleanse Iraq of "evil."
On April 4, the Mahdi Army was directed to begin launching attacks on coalition targets and to seize control from the nascent U.S.-trained Iraqi security forces.
The Mahdi Army, which by then numbered from 3,000 to 10,000 men, organized quickly escalating violent riots and then a coordinated assault, surprising coalition and Iraqi forces and seizing control of Najaf, Kufa, al-Kut, and parts of Baghdad and southern cities like Nasiriyah, Amarah, and Basra.
Soon, combat was erupting in many urban centers of southern and central portions of Iraq as U.S. forces attempted to maintain control and prepared for a counteroffensive.
The intended Marine strategy of patrols, less aggressive raids, humanitarian aid, and close cooperation with local leaders was quickly suspended and the U.S. decided that it was time for a major assault to clear the city of insurgents.
Political pressure began to build on the United States and the Governing Council of Iraq as the hospital of Fallujah continued to report high numbers of civilian casualties, inflaming further the Iraqi people and Muslim world in general.
Pentagon leaders, fearing that continuing the effort to capture the city might further inflame a larger revolt against Coalition authority, pulled back the forces.
U.S. forces launched only occasional armored forays into Samarra and Baquba, while about half a dozen small forts were maintained by the U.S. Marines in Ramadi, with the surrounding territory in the city controlled by rebels.
American ground forces remained outside of Fallujah, though regular air strikes were conducted on alleged safehouses of Abu Musab al-Zarqawi's followers in the city.
Over the next three months, over 1,500 Mahdi Army militiamen, several hundred civilians, and dozens of coalition soldiers were killed as the U.S. gradually took back the southern cities.
On June 28, 2004, the occupation was formally ended by the Coalition, which transferred power to a new Iraqi government led by Prime Minister Ayad Allawi.
While no group claimed responsibility, U.S. military and Iraqi Transitional government officials attributed the attacks to Sunni militants linked to Al-Qaeda in Iraq.
[35][36] The Red Cross stated in 2008 that Iraq's humanitarian situation was among the most critical in the world, with millions of Iraqis forced to rely on insufficient and poor-quality water sources.