John Prados and Christopher Ames provide the second of three articles at the National Security Archives on decision-making in the Iraq War, Was There Even a Decision? 10/01/2010:
President George W. Bush and Prime Minister Tony Blair, the record suggests, made their real decision privately and restricted knowledge to a very few individuals. Information from participants, especially on the British side, also increasingly suggests that even between the U.S. and British governments, and within the Bush administration itself, subordinate officials were kept in ignorance of leaders’ real intentions. Evidence indicates the decision was made very early, long before ultimatums to Iraq or other diplomatic action. An alternative view, that leaders ordered up contingency plans for war and then simply implemented them without further consideration based on the mechanics of military and alliance planning, offers an equally bleak picture of the disastrous Operation Iraqi Freedom. ...
Documenting the origins of the Iraq war are an increasing array of declassified documents, a public record of the time, and a growing body of reflections, recollections, and memoirs. This material sustains the narrative of a drive toward war but not one of conflict resolution. Such diplomacy as took place was designed to recruit allies for an invasion or to coerce the Saddam government into admitting international teams of weapons inspectors—not to disarm Iraq but to justify invasion. [my emphasis]
One of the effects of the 9/11 attacks was, thanks to the Cheney-Bush Administration's inclination and Congress' unwillingness to restrain it, was that it became common US policy to engage in acts of war under the cover of covert action, which the Obama Administration is tragically continuing today:
On February 12  Secretary of State Colin Powell told a Senate committee that regime change in Iraq was a longstanding U.S. policy and in the best interests of the Iraqi people.(Note 7) Powell hastened to add that President Bush had no invasion plan on his desk, which was accurate only because the project was not actually on his desk (Franks had presented his latest concept to Bush five days earlier). "I will reserve whatever options I have, I'll keep them close to my vest," President Bush said at a February 13 news conference. Several days later he signed a new presidential finding authorizing covert operations against Iraq, and CIA advance teams visited the Kurdish region of that country within days. During all of this no U.S. diplomatic initiative was underway to encourage the Saddam regime to show the real state of its armaments programs. ...
Instead American diplomacy sought to build the foundation for war. ...
In February, with President Bush examining attack plans and issuing action orders to the CIA, the State Department held a meeting of its Middle East chiefs-of-mission, chaired by William Burns, the assistant secretary for that region. The assembled diplomats worried that a war in Iraq would last at least five years and that there would be an insurgency after two at the most. [my emphasis in bold]
The no-fly zones established by Old Man Bush's Administration after the Gulf War in 1991 and continued throughout the Clinton Administration - including the serious (and spectacularly badly named) Operating Desert Fox - also provided a means for the Cheney-Bush Administration to take acts of war while falsely claiming to the American public and the world their intention to avoid war:
Most aggressive of all the U.S. measures would be what was done in the so-called "No-Fly Zones." These had been established after the 1991 Gulf War to prevent Saddam from using air forces to further suppress revolts in Kurdistan and in southern Iraq. Under operations called Northern Watch (flying from Turkey) and Southern Watch (flying from Saudi Arabia and Kuwait), the U.S. and Britain, with France until 1994, patrolled Iraqi skies. When fired upon by Saddam’s air defenses they shot back. Legal justification for this aerial interdiction, weak to begin with, had eroded further with the evaporation of internal opposition to Saddam. Yet the Bush administration not only continued the aerial suppression but quietly converted it into a low intensity strategic bombing campaign, finally aiming at targets whose destruction would facilitate an invasion. The campaign, carried out from the south, would be dubbed "Southern Focus." Military options for the campaign were developed early in 2002 and refined over a period of months. Saudi Arabia, informed of the plan, denied the use of its air bases for this purpose, necessitating a shift of U.S. strike aircraft to Qatar that was completed in May. The attacks began soon thereafter, following a hiatus of several months. By July  the aircraft were attacking Iraqi communications systems, not merely air defense sites—targets that would be important to Baghdad in responding to an invasion. [my emphasis]
The information Prados and Ames discuss in this article strongly reinforce the idea that the Cheney-Bush Administration had made a definite decision at latest by the end of February 2002 to go to war with Iraq. (The "Downing Street Memo" had previously provided convincing documentation that such a decision had been taken no later than July 2002.) For example:
While the Blair government tried to induce the Bush administration to adopt a more sophisticated diplomatic posture, U.S. war preparations moved steadily ahead. According to CENTCOM deputy commander General Michael DeLong, for 18 months until the war began—that is, beginning in October 2001 - each time a military exercise was held in the region the U.S. sent more troops than required, then left some behind. By February special operations forces were already being diverted from the Afghan war to prepare for Iraqi operations — so many that General Franks complained to a senior senator that the practice was impinging on CENTCOM’s ongoing operations in Afghanistan. Successive briefings on the evolving war plan have been referred to already. Among these, spy chieftain George Tenet met with Kurdish leaders that month to assure them that America was, in fact, coming to Iraq. On March 21 Franks flew to Germany for the first full staff conference of the field command that would actually conduct the war, while two days later in Washington, the Joint Chiefs of Staff began a wargame to examine the feasibility of one version of the invasion plan. The Chiefs listened to Franks’ report on his German trip at the Pentagon on March 29. Orders to the 101st Airborne Division to prepare for deployment to the combat theater were issued in April and electrified the U.S. Army.
Prados and Ames conclude:
In summary, we have a record of military planning which President George Bush demanded early on, pushed steadily, and repeatedly encouraged. The completion of the war plan by August 2002 and the even earlier initiation of an offensive air campaign against Iraq and preliminary force deployments to the theater do not track with the narrative that no decision had yet been made. The parallel record of Bush administration hostility to multilateral diplomacy (to verify Iraq's status through international inspections) accords with the view that Bush was determined to move forward. The robust efforts at secrecy — extending even to allies — suggest an attempt to prevent interference with the administration's course by limiting knowledge of its real actions. The Bush refrain that there were no war plans on his desk - repeated verbatim on occasion by Secretary Powell and security adviser Condoleezza Rice - is consistent with the interpretation that the president had already made his decision; or alternatively, with the view that this formed part of the secrecy program; or else with the deliberately narrow proposition that because the plans were at CENTCOM they were not technically "on" Bush’s desk.
George Bush's engagement with Tony Blair at Crawford [April 2002] suggests that if he made a conscious choice it was at or before that date. The evidence is also congruent with a Bush decision in 2001. Administration refusal to be deterred by the negative results of the March 2002 Cheney Middle East tour carries the same implication. Bush's delay of at least four months in fulfilling his commitment to Blair to seek UN inspections, doing so only after the onset of public protest, plus renewed pressures from Blair as well as Powell, also indicate that war, not diplomacy, was the preferred course. This intense focus on achieving the conditions for war instead of solving an international problem led to critical faults in military planning and diplomatic action that made the Iraq war the mess it became. [my emphasis]