Causes leading up to Operation Iraqi Freedom I (Gulf War II).

        First, there was the lingering tension and hostility left over from the Gulf War of 1991 (Operation Desert Shield/Storm), in which Iraqi occupation troops were forced out of Kuwait.

        As a result of the war, the Iraqi government agreed to surrender and/or destroy several types of weapons, including their SCUD missiles and various Weapons of Mass Destruction (WMD’s). The United Nations were allowed to send weapons inspectors to confirm the destruction of Iraqi weapons and also to search for prohibited weapons believed to be in hiding.

        Two "No Fly Zones" (Operation Northern/Southern Watch) were established over northern and southern Iraq for the protection of Iraqi minority groups in opposition to the Saddam Hussein government (Operation Provide Comfort). Over these two zones, Allied aircraft patrolled the air in order to prevent Iraqi aircraft from attacking northern Kurds or southern Shiites. Over the years, Iraqi air-defense forces fired missiles and other weapons at the Allied warplanes (mostly American and British planes) in unsuccessful attempts to shoot them down. In response to these attempted shoot-downs, Allied warplanes often responded by bombing the air-defense sites and the radar installations associated with them.

        In 1998, under Iraqi pressure, the UN weapons inspectors left Iraq, prompting the United States to launch a severe three-day bombing campaign called "Operation Desert Fox." Following this, Iraqi forces significantly increased attempts to challenge the Allied planes patrolling the No-Fly Zones, thereby also causing an increase in the Allied bombing of Iraqi targets.

        Second, following the terrorist attacks on the United States on September 11, 2001. Although the US government admitted they had no evidence of any direct Iraqi involvment in the attacks of 11 September 2001, U.S. intelligence agencies identified links between al-Qaida and other Muslim extremest groups who were alleged to be receiving training and support in and from Iraq (these links would later be confirmed by seized Iraqi intelligence unit documents). Using the potential threat of Saddam-supplied Weapons of Mass Destruction in the hands of terrorists, the U.S. government and the United Nations increasingly insisted on total Iraqi disarmament. With initial backing by the UN Security Council, the United States encircled Iraq with growing military forces, leading Iraq to permit UN weapons inspectors back into the country.

        By early 2003, however, the U.S. and British governments claimed that Iraq was not cooperating fully with the UN inspectors. It was also suspected that France, Russia and Germany were resisting the US efforts to engage further actions by the UN Security Council because of backdoor economic and illegal arms and equipment sales activity that was expressly banned by UN approved sanctions already in place under the Oil for Food Program (the suspicions were later confirmed to be true).

Edited from, The History Guy, Gulf War II, Time Line, historyguy.com