Shortly after the September 11 attacks, the United States under the administration of George W. Bush, actively pressed for military action against Iraq, claiming that Iraqi leader Saddam Hussein was developing weapons of mass destruction and having ties with al-Qaeda. The United States and United Kingdom argued that Iraq's activities posed a threat to the international community.
After the Gulf War in 1991, the U.S. and the U.K. pursued a policy of containment towards Iraq. Containment encompassed a United Nations inspections regime that was tasked with disarming Iraq of weapons of mass destruction, which was linked to an comprehensive embargo on that country. In addition, the U.S. and U.K. patrolled no fly zones that barred Iraqi aircraft from operating in northern and southern Iraq. However, by the end of the 1990s, containment eroded as relations became increasingly strained between the U.N. and Iraq, which ultimately culminated in the weapons inspectors being withdrawn from the country in late 1998. The U.S. and U.K. retaliated with a bombing campaign against Iraqi military targets. Following Desert Fox, Iraq openly challenged U.S. and U.K. aircraft patrolling the no fly zones, attempting to shoot down military aircraft. Concurrently, U.N. sanctions were becoming less enforced, as Iraq was able to manipulate the sanctions regime in its favor to convince more countries to lift the sanctions altogether.
As containment eroded, beginning in the late 1990s neoconservatives argued for the overthrow of Saddam Hussein's regime and democratization of Iraq. They justified overthrow on the basis that Ba'athist Iraq posed a direct threat to American security by threatening Middle East stability and secure access to oil with its weapons of mass destruction and missile programs, and that the United Nations was an ineffective tool in confronting this threat. Neoconservative advocacy would lead to the passing of the Iraq Liberation Act in late 1998, making regime change in Iraq as official U.S. policy. Following the election of George W. Bush as president in 2000, the U.S. moved towards a more aggressive Iraq policy. The Republican Party's campaign platform in the 2000 election called for "full implementation" of the Iraq Liberation Act as "a starting point" in a plan to "remove" Saddam. Many neoconservatives would take up key positions in the Bush administration.
In the aftermath of the September 11 attacks, elements within the Bush administration believed that Iraq shared responsibility for the attacks, as well as having ties to al-Qaeda. Believing that a state sponsor was involved, many within the administration concurrently harbored a distrust towards the U.S. intelligence community for underestimating threats, and instead preferred utilizing outside analysis and intelligence from the Iraqi opposition that alleged an Iraq-al-Qaeda connection, as well as allegations that Iraq was developing weapons of mass destruction. Although military action was initially deferred in favor of invading Afghanistan, from September 2002 the U.S. began to formally present its case for action against Iraq at the United Nations. In November, the UN Security Council unanimously passed Resolution 1441, stating that Iraq was in material breach with its disarmament obligations and giving Iraq "a final opportunity to comply" that had been set out in several previous resolutions (Resolutions 660, 661, 678, 686, 687, 688, 707, 715, 986, and 1284). Concurrently, an elaborate public relations campaign was waged to market military action to both the American and British publics, culminating in then-Secretary of State Colin Powell's February 2003 address to the Security Council.
After failing to gain UN support for an UN authorization for an invasion, the U.S., together with the U.K. and small contingents from Australia, Poland, and Denmark, launched an invasion on 20 March 2003 under the authority of UN Security Council Resolution 660 and United Nations Security Council Resolution 678. Following the invasion, no evidence of an active WMD program or ties to al-Qaeda was ever found.
Background
Pre-Gulf War
Throughout the Cold War, Iraq had been an ally of the Soviet Union, and there was a history of friction between Iraq and the United States. The U.S. had backed Pahlavi Iran as means of maintaining Gulf stability, and the latter had been an adversary of Iraq. Shah Mohammed Reza Pahlavi distrusted the Ba'athist government in Iraq, which he considered a "bunch of thugs and murderers." In April 1969, Iran abrogated the 1937 treaty over the Shatt al-Arab and Iranian ships stopped paying tolls to Iraq when they used the Shatt al-Arab.Karsh, Efraim The Iran–Iraq War 1980–1988, London: Osprey, 2002 pp. 7–8 The Shah argued that the 1937 treaty was unfair to Iran because almost all river borders around the world ran along the thalweg, and because most of the ships that used the Shatt al-Arab were Iranian.Bulloch, John and Morris, Harvey The Gulf War, London: Methuen, 1989 p. 37. Iraq threatened war over the Iranian move, but on 24 April 1969, an Iranian tanker escorted by Iranian warships (Joint Operation Arvand) sailed down the Shatt al-Arab, and Iraq—being the militarily weaker state—did nothing.Karsh, Efraim The Iran–Iraq War 1980–1988, London: Osprey, 2002 p. 8 Mohammad Reza financed Kurdish separatist rebels in Iraq, and to cover his tracks, armed them with Soviet weapons which Israel had seized from Soviet-backed Arab regimes, then handed over to Iran at the Shah's behest. On 7 May 1972, the Shah told a visiting President Richard Nixon that the Soviet Union was attempting to dominate the Middle East via its close ally Iraq, and that to check Iraqi ambitions would also be to check Soviet ambitions.Milani, Abbas. The Shah, London: Macmillan, 2011, p. 360. Nixon agreed to support Iranian claims to have the thalweg in the Shatt al-Arab recognised as the border and to generally back Iran in its confrontation with Iraq.
From October 1972 until the abrupt end of the Kurdish intervention after March 1975, the CIA "provided the Kurds with nearly $20 million in assistance," including 1,250 tons of non-attributable weaponry. The main goal of U.S. policy-makers was to increase the Kurds's ability to negotiate a reasonable autonomy agreement with the government of Iraq. To justify the operation, U.S. officials cited Iraq's support for international terrorism and its repeated threats against neighboring states, including Iran (where Iraq supported Baluchi and Arab separatists against the Shah) and Kuwait (Iraq launched an unprovoked attack on a Kuwaiti border post and claimed the Kuwaiti islands of Warbah and Bubiyan in May 1973), with Haig remarking: "There can be no doubt that it is in the interest of ourselves, our allies, and other friendly governments in the area to see the Ba'thi regime in Iraq kept off balance and if possible overthrown." In 1975, Iran and Iraq signed the Algiers Accord, which granted Iran equal navigation rights in the Shatt al-Arab as the thalweg was now the new border, while Mohammad Reza agreed to end his support for Iraqi Kurdish rebels.
In February 1979, the Iranian Revolution ousted the American-backed Shah from Iran, losing the United States one of its most powerful allies. That November, the revolutionary group Muslim Student Followers of the Imam's Line, angered that the ailing Shah had been allowed into the United States for medical treatment, occupied the American embassy in Tehran and took American diplomats hostage with the advance approval of the leader of Iran, Ayatollah Ruhollah Khomeini. Diplomatic relations between Iran and the United States were severed shortly after. Concurrently, Iraqi-Iranian relations were deteriorating as Khomeini was attempting to export the Islamic Revolution to the Arab world, calling for existing regimes to be overthrown in Islamist revolutions. Saddam, a secularist and an Arab nationalist, perceived Iran's Shia Islamism as an immediate and existential threat to his Ba'ath Party and thereby to Iraqi society as a whole.
Iraq invaded Iran on 22 September 1980, first launching airstrikes on numerous targets in Iran, including the Mehrabad Airport of Tehran, before occupying the oil-rich Iranian province of Khuzestan, which also has a sizable Arab minority. The invasion was initially successful, as Iraq captured more than 25,900 km2 of Iranian territory by 5 December 1980. After making some initial gains, Iraq's troops began to suffer losses from human wave attacks by Iran. By mid-1982, the war's momentum had shifted decisively in favor of Iran, which invaded Iraq to depose Saddam's government.cf. Although the U.S. was officially neutral at first, the prospect of an expansionist Iran alarmed many in the Reagan administration, leading the U.S. to abandon neutrality. The U.S. then joined in alongside the Soviet Union, France, China, and the Gulf states such as Saudi Arabia and Kuwait to bolster Iraq, helping to provide several billion dollars' worth of economic aid, the sale of dual-use technology, non-U.S. origin weaponry, military intelligence, and special operations training.Friedman, Alan. Spider's Web: The Secret History of How the White House Illegally Armed Iraq, Bantam Books, 1993. Timmerman, Kenneth R. The Death Lobby: How the West Armed Iraq. New York, Houghton Mifflin Company, 1991. In a US bid to open full diplomatic relations with Iraq, the country was removed from the US list of State Sponsors of Terrorism. Following this, the United States extended credits to Iraq for the purchase of American agricultural commodities, the first time this had been done since 1967. More significantly, in 1983 the Baathist government hosted United States special Middle East envoy Donald Rumsfeld, to cultivate U.S.-Iraq ties. All of these initiatives prepared the ground for Iraq and the United States to reestablish diplomatic relations in November 1984. Iraq was the last of the Arab countries to resume diplomatic relations with the U.S.
The U.S. provided critical battle planning assistance at a time when U.S. intelligence agencies knew that Iraqi commanders would employ chemical weapons in waging the war, according to senior military officers with direct knowledge of the program. The U.S. carried out this covert program even as it publicly condemned Iraq for its use of poison gas, especially after Iraq attacked Kurdish villagers in Halabja in March 1988.New York Times, August 18, 2002. According to Iraqi documents, assistance in developing chemical weapons was obtained from firms in many countries, including the United States, West Germany, the Netherlands, the United Kingdom, and France. A report stated that Dutch, Australian, Italian, French and both West and East German companies were involved in the export of raw materials to Iraqi chemical weapons factories.