In a 696-page account, army historians fault military and political leaders for focusing excessively on toppling Saddam Hussein in 2003 without looking towards a broader transition towards a stable society. Actions by the former defence secretary Donald Rumsfeld and the top US commander during the Iraq invasion, Tommy Franks, are singled out in the study, which was delayed for six months to allow senior army figures to review drafts.
"The transition to a new campaign was not well thought out, planned for and prepared for before it began," says the history, On Point II: Transition to the New Campaign, published by an internal army thinktank called the contemporary operations study team. "The assumptions about the nature of the post-Saddam Iraq on which the transition was planned proved to be largely incorrect."
It says Franks took senior colleagues by surprise by moving to a slimmed-down, short-staffed headquarters shortly after the invasion of Iraq was complete. He told his officers to be ready to cut back on forces in preparation for "an abbreviated period of stability operations".
The study describes defence chiefs in Washington as ambivalent from the start about a "ponderous, troop-heavy, logistics intensive and costly" ongoing campaign to restore stability. "The [department of defence] did commit resources to the planning of post-invasion operations," it says. "In retrospect, however, the overall effort appears to have been disjointed and, at times, poorly coordinated, perhaps reflecting the department's ambivalence towards nation-building."
A hotly contested debate continues to rage over blame for Iraq's sustained bloodletting. Britain's former chief of general staff, Sir Mike Jackson, suggested in his memoirs last year that Rumsfeld's "intellectually bankrupt" management undermined post-war planning by the state department.
Colleagues of Rumsfeld, such as his former under-secretary Douglas Feith, have suggested that the Pentagon was let down by poor intelligence from the CIA. Since standing down in 2006, Rumsfeld has been working on a book of his own.
The blunt language used in the army's historical study is effectively endorsed by the force's present chiefs. The document is based on 200 interviews with participants including the present chief of staff, General George Casey.
Senior officers complain that their units were given little or no training for so-called stability operations. Troops were not given plans for postwar roles until the invasion was under way. There was an incorrect assumption that Iraqi ministries would continue to operate even after the country's leader was toppled.
Colonel Thomas Torrance, commander of an artillery division, told the authors: "I can remember asking the question during our war gaming and the development of the plan, 'OK, we are in Baghdad. What next?' No real good answers came forth."
The army's then vice-chief of staff, Jack Keane, spoke of his misgivings about the small scale of the force's headquarters in Iraq after George Bush declared military victory in May 2003, describing the downsizing as "a recipe for disaster".
William Wallace, head of the army's training and doctrine command, told the authors: "We had the wrong assumptions and therefore we had the wrong plan to put into play."
The Iraqi insurgency has led to soul-searching and changes of policy within the US army. In February, the army published a new field manual placing more emphasis on nation-building, peacekeeping and "unconventional" warfare.
© Guardian News and Media Limited 2008