The Iraq War began with the US-led 2003 invasion of Iraq. The Government of Canada did not at any time formally declare war against Iraq, and the level and nature of this participation, which changed over time, was controversial. Canada's intelligence services repeatedly assessed that Iraq did not have an active WMD program.
While Canada had previously participated in military action against Iraq in the Gulf War of 1991, it refused to declare war against Iraq without United Nations Security Council approval. Even so, Prime Minister Jean Chrétien said on 10 October 2002 that Canada would be part of a military coalition to invade Iraq if it were sanctioned by the United Nations. However, when the United States and the United Kingdom subsequently withdrew their diplomatic efforts to gain that UN sanction, Jean Chrétien announced in Parliament on 17 March 2003 that Canada would not participate in the pending invasion. Nevertheless, he offered the US and its soldiers his moral support. Two days earlier, a quarter million people in Montreal had marched against the pending war. Major anti-war demonstrations had taken place in several other Canadian cities.
Canada's relation to the Iraq War that began in 2003 was unlike Canada's role in the 2001 invasion of Afghanistan because it was far less direct. About a hundred Canadian exchange officers, on exchange to American units, participated in the invasion of Iraq. It has been reported that Canadian troops in the region numbered fewer than only three other participating countries. The War also affected Canada in the form of protests and counter-protests related to the conflict, and United States military members who sought refuge in the country after deserting their posts to avoid deployment to Iraq—but who, unlike as with the Vietnam War, were mostly returned by Canada forthwith to the United States.
Decision not to participate
In September 2002, the prime minister of Canada Jean Chrétien informed both British Prime Minister Tony Blair and U.S. President George W. Bush that Canada's participation in any coalition against Iraq would be contingent on having the support of the United Nations (UN), or the majority of the international community. The official policy of the Canadian government was carefully worded so that the Canadian diplomats could still play an important factor in the pre-war diplomacy with Iraq. Additionally, while it was their preference to have the approval of the United Nations Security Council (UNSC), the policy still permitted the Canadian government to participate in the invasion if China or Russia vetoed a resolution that was supported by the rest of the UNSC. The Canadian government maintained this position in the lead-up to the invasion of Iraq.
During the lead-up to the conflict, Chrétien maintained contact with Ricardo Lagos, the president of Chile, and Vicente Fox, the president of Mexico. Lagos and Fox had noted they were under pressure from the United States to join the coalition, although both told Chrétien that they would refuse to participate if Canada does so as well.
The decision by the UN on whether or not to sanction the invasion rested on two elements, a discussion of international law, including the Nuremberg Principles on preemptive war; and the UN inspections for Iraq's alleged possession of weapons of mass destruction (WMD). However, because the coalition failed to have the UN sanction their intervention, Chrétien advised Governor General Adrienne Clarkson not to have Canada join the "coalition of the willing" that was central to the 2003 invasion of Iraq. On 17 March 2003, two days before the invasion of Iraq began, Chrétien publicly announced his decision to not join the coalition on the floor of the Canadian House of Commons. His decision to not privately inform the US government before he publicly announced his decision contributed to breakdown in Bush and Chrétien's relationship in mid-2003.
Domestic opinion
By August 2002, Canadian officials held no doubts that the United States was planning on targeting Iraq. On 14 August 2002, Chrétien received a memorandum from Alex Himelfarb, the clerk of the Canadian privy council where he bluntly states that US actions against Iraq were an attempt to implement regime change. The majority of the members of the Cabinet of Canada had little general knowledge of Iraq, although most were sceptical of the American cause. However, some cabinet members held concerns that not joining the coalition would damage Canada-US relations because American rhetoric had linked Iraq to the vital interests of the United States.