[3] Rationales for opposition include the belief that the war is illegal according to the United Nations Charter,[4] or would contribute to instability both within Iraq and the wider Middle East.
Although there was significant opposition to the idea in the months preceding the attack, polls taken during the invasion showed that a majority of US citizens supported their government's action.
Noam Chomsky said: Poll results available from Gallup International, as well as local sources for most of Europe, West and East, showed that support for a war carried out "unilaterally by America and its allies" did not rise above 11 percent in any country.
Others did accept a limited right for military intervention in foreign countries, but nevertheless opposed the invasion on the basis that it was conducted without United Nations' approval and was hence a violation of international law.
There was also skepticism of U.S. claims that Iraq's secular government had any links to Al-Qaeda, the Islamic fundamentalist terrorist group considered responsible for the September 11 attacks on the World Trade Center and Pentagon.
Administration officials denied these charges, and scholar Jeff Colgan writes that "there is still no consensus on the degree to which oil played a role" in the Iraq War.
Investigations after the invasion failed to produce evidence of WMDs in Iraq (apart from a very small number of degraded chemical weapons shells located after the Iran–Iraq War ended in 1988).
Consistent with the anti-war sentiment of the protests, in the months leading up to the Iraq War, American public opinion heavily favored a diplomatic solution over immediate military intervention.
A January 2003 CBS News/New York Times poll found that 63% of Americans wanted President Bush to find a diplomatic solution to the Iraq situation, compared with 31% who favored immediate military intervention.
Sheehan's role as an anti-war leader began with her camping out near President Bush's ranch in Crawford, Texas, and continued with a nationwide tour and trips to Europe and South America.
Several prominent members of the military and national security communities, particularly those who favor a more realist approach to international relations, have been critical of both the decision to invade Iraq and the prosecution of the War.
[15] In a 2002 book, Scott Ritter, a Nuclear Weapons Inspector in Iraq from 1991 to 1998, argued against an invasion and expressed doubts about the Bush Administration's claims that Saddam Hussein had a WMD capability.
He wrote an August 15, 2002 editorial in The Wall Street Journal entitled "Don't attack Saddam," arguing that the war would distract from the broader fight against terrorism and the Israeli–Palestinian conflict, which should be the U.S.'s highest priority in the Middle East.
"[21] On February 13, 2003, Ambassador Joseph Wilson, former chargé d'affaires in Baghdad, resigned from the Foreign Service and publicly questioned the need for another war in Iraq.
In addition to diverting funds from the fight against al-Qaeda, Clarke argued that the invasion of Iraq would actually bolster the efforts of Osama bin Laden and other Islamic radicals, who had long predicted that the U.S. planned to invade an oil-rich Middle Eastern country.
[35] In October 2007, Lieutenant General Ricardo Sanchez, former commander of coalition forces in Iraq, called the 2007 "surge" a "flawed strategy", and suggested that the political leadership in the US would have been court martialed for their actions, had they been military personnel.
[37] Soon after the war began, 67% of surveyed US soldiers in Iraq told Stars and Stripes that the invasion was worthwhile, though half described their units' morale as "low.
"[49] In the 2008 U.S. presidential campaign, candidates Representatives Ron Paul and Dennis Kucinich, Senators Barack Obama, Chris Dodd and Mike Gravel were some of the most outspoken critics of the Iraq War.
France's then-Foreign Minister, Dominique de Villepin received loud applause for his speech against the Iraq War at the United Nations on February 14, 2003.
Prominent politicians and other individuals expressing anti-war views included: Tory MP Ken Clarke,[60] Charles Kennedy, Menzies Campbell, Tony Benn, George Galloway, future Labour party leader Jeremy Corbyn, Chris Martin, Damon Albarn, Ms. Dynamite, and Bianca Jagger.
In a statement giving his reasons for resigning he said: Our interests are best protected not by unilateral action but by multilateral agreement and a world order governed by rules.
"[61] and "The reality is that Britain is being asked to embark on a war without agreement in any of the international bodies of which we are a leading partner—not NATO, not the European Union and, now, not the Security Council.
"[62]Secretary of State for International Development Clare Short supported the government's resolution in the House of Commons and remained in the Cabinet for two months but eventually resigned on 12 May.
Opinion polls showed that the population of nearly all countries opposed a war without UN mandate, and that the view of the United States as a danger to world peace had significantly increased.
"[70][71] On September 13, 2002, US Catholic bishops signed a letter to President Bush stating that any "preemptive, unilateral use of military force to overthrow the government of Iraq" could not be justified at the time.
US civil-rights leader the Reverend Jesse Jackson condemned the planned invasion, saying in February 2003 that it was not too late to stop the war and that people "must march until there is a declaration of peace and reconciliation.
"[78] In the lead-up to the invasion, a project by Talking Heads frontman David Byrne and comedian Russell Simmons was formed which was called "Musicians United to Win Without War.
After the simultaneous demonstrations, on February 15, 2003, the largest in total turnout, New York Times writer Patrick Tyler claimed that they showed that there were two superpowers on the planet: the United States and world public opinion.
However, those who remained opposed to the U.S. presence had to determine their approach to the developing armed insurgency and peaceful opposition to the occupation carried out by groups like the Worker-communist Party of Iraq (WCPI).
He cites in turn Mahmood Ketabchi of the WCPI, who criticizes Iraqi guerrilla groups for Baathist and Islamist connections, and attacks Ruder's view as a "Left Nationalism" which ignores divisions within Iraq.