Iraq War, (2003–11), conflict in Iraq that consisted of two phases. The first of these was a brief, conventionally fought war in March–April 2003, in which a combined force of troops from the United States and Great Britain (with smaller contingents from several other countries) invaded Iraq and rapidly defeated Iraqi military and paramilitary forces. It was followed by a longer second phase in which a U.S.-led occupation of Iraq was opposed by an insurgency. After violence began to decline in 2007, the United States gradually reduced its military presence in Iraq, formally completing its withdrawal in December 2011. American military casualties in the conflict included some 4,500 service members killed and some 32,000 others wounded.

(Read Britannica’s interview with Jimmy Carter on the Iraq War and world affairs.)

Prelude to war

Iraq’s invasion of Kuwait in 1990 ended in Iraq’s defeat by a U.S.-led coalition in the Persian Gulf War (1990–91). However, the Iraqi branch of the Baʿath Party, headed by Saddam Hussein, managed to retain power by harshly suppressing uprisings of the country’s minority Kurds and its majority Shiʿi Arabs. To stem the exodus of Kurds from Iraq, the allies established a “safe haven” in northern Iraq’s predominantly Kurdish regions, and allied warplanes patrolled “no-fly” zones in northern and southern Iraq that were off-limits to Iraqi aircraft. Moreover, to restrain future Iraqi aggression, the United Nations (UN) implemented economic sanctions against Iraq in order to, among other things, hinder the progress of its most lethal arms programs, including those for the development of nuclear, biological, and chemical weapons. (See weapon of mass destruction.) UN inspections during the mid-1990s uncovered a variety of proscribed weapons and prohibited technology throughout Iraq. That country’s continued flouting of the UN weapons ban and its repeated interference with the inspections frustrated the international community and led U.S. Pres. Bill Clinton in 1998 to order the bombing of several Iraqi military installations (code-named Operation Desert Fox). After the bombing, however, Iraq refused to allow inspectors to reenter the country, and during the next several years the economic sanctions slowly began to erode as neighboring countries sought to reopen trade with Iraq.

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In 2002 the new U.S. president, George W. Bush, argued that the vulnerability of the United States following the September 11 attacks of 2001, combined with Iraq’s alleged continued possession and manufacture of weapons of mass destruction (an accusation that was later proved erroneous) and its support for terrorist groups—which, according to the Bush administration, included al-Qaeda, the perpetrators of the September 11 attacks—made disarming Iraq a renewed priority. UN Security Council Resolution 1441, passed on November 8, 2002, demanded that Iraq readmit inspectors and that it comply with all previous resolutions. Iraq appeared to comply with the resolution, but in early 2003 President Bush and British Prime Minister Tony Blair declared that Iraq was actually continuing to hinder UN inspections and that it still retained proscribed weapons. Other world leaders, such as French Pres. Jacques Chirac and German Chancellor Gerhard Schröder, citing what they believed to be increased Iraqi cooperation, sought to extend inspections and give Iraq more time to comply with them. However, on March 17, seeking no further UN resolutions and deeming further diplomatic efforts by the Security Council futile, Bush declared an end to diplomacy and issued an ultimatum to Saddam, giving the Iraqi president 48 hours to leave Iraq. The leaders of France, Germany, Russia, and other countries objected to this buildup toward war.

The 2003 conflict

When Saddam refused to leave Iraq, U.S. and allied forces launched an attack on the morning of March 20; it began when U.S. aircraft dropped several precision-guided bombs on a bunker complex in which the Iraqi president was believed to be meeting with senior staff. This was followed by a series of air strikes directed against government and military installations, and within days U.S. forces had invaded Iraq from Kuwait in the south (U.S. Special Forces had previously been deployed to Kurdish-controlled areas in the north). Despite fears that Iraqi forces would engage in a scorched-earth policy—destroying bridges and dams and setting fire to Iraq’s southern oil wells—little damage was done by retreating Iraqi forces; in fact, large numbers of Iraqi troops simply chose not to resist the advance of coalition forces. In southern Iraq the greatest resistance to U.S. forces as they advanced northward was from irregular groups of Baʿath Party supporters, known as Saddam’s Fedayeen. British forces—which had deployed around the southern city of Basra—faced similar resistance from paramilitary and irregular fighters.

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In central Iraq units of the Republican Guard—a heavily armed paramilitary group connected with the ruling party—were deployed to defend the capital of Baghdad. As U.S. Army and Marine forces advanced northwestward up the Tigris-Euphrates river valley, they bypassed many populated areas where Fedayeen resistance was strongest and were slowed only on March 25 when inclement weather and an extended supply line briefly forced them to halt their advance within 60 miles (95 km) of Baghdad. During the pause, U.S. aircraft inflicted heavy damage on Republican Guard units around the capital. U.S. forces resumed their advance within a week, and on April 4 they took control of Baghdad’s international airport. Iraqi resistance, though at times vigorous, was highly disorganized, and over the next several days army and Marine Corps units staged raids into the heart of the city. On April 9 resistance in Baghdad collapsed, and U.S. soldiers took control of the city.

On that same day Basra was finally secured by British forces, which had entered the city several days earlier. In the north, however, plans to open up another major front had been frustrated when the Turkish government refused to allow mechanized and armored U.S. Army units to pass through Turkey to deploy in northern Iraq. Regardless, a regiment of American paratroopers did drop into the area, and U.S. Special Forces soldiers joined with Kurdish peshmerga fighters to seize the northern cities of Kirkuk on April 10 and Mosul on April 11. Saddam’s hometown of Tikrīt, the last major stronghold of the regime, fell with little resistance on April 13. Isolated groups of regime loyalists continued to fight on subsequent days, but the U.S. president declared an end to major combat on May 1. Iraqi leaders fled into hiding and were the object of an intense search by U.S. forces. Saddam Hussein was captured on December 13, 2003, five months after his two sons, Uday and Qusay Hussein, who were central figures in their father’s brutal 24-year rule, had been killed in a shoot-out with American troops after the brothers had been found hiding in a private residence. Saddam was subsequently convicted of crimes against humanity and was executed on December 30, 2006.

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