Former defense secretary Donald Rumsfeld, that master of the tart zinger, now concedes he went too far with some. The man who more than any other in the Bush administration personified bravado and self-assuredness has come to regret saying "Stuff happens" about the early looting in postwar Iraq. He admits his quip about "old Europe" - meaning Germany and France - not supporting the use of force in Iraq was hardly deft diplomacy.

As for declaring, as he did in the first days after the invasion of Iraq, "We know where they are," referring to suspected stockpiles of weapons of mass destruction - well, Rumsfeld would like to take that one back, too.

But Rumsfeld still can't resist - in a memoir due out next week - taking a few pops at former secretaries of state Colin L. Powell and Condoleezza Rice as well as at some lawmakers and journalists. He goes so far as to depict former president George W. Bush as presiding over a national security process that was marked by incoherent decision-making and policy drift, most damagingly on the war in Iraq.

Much of Rumsfeld's retrospective reinforces earlier accounts of a dysfunctional National Security Council riven by tensions between the Pentagon and State Department, which many critics outside and within the Bush administration have blamed on him. Speaking out for the first time since his departure from office four years ago, the former Pentagon leader offers a vigorous explanation of his own thoughts and actions and is making available on his Web site (www.rumsfeld.com) many previously classified or private documents.

Sounding characteristically tough and defiant in the 800-page autobiography "Known and Unknown," Rumsfeld remains largely unapologetic about his overall handling of the Iraq conflict and concludes that the war has been worth the costs. Had the government of Saddam Hussein remained in power, he says, the Middle East would be "far more perilous than it is today."

Addressing charges that he failed to provide enough troops for the war, he allows that, "In retrospect, there may have been times when more troops could have helped." But he insists that if senior military officers had reservations about the size of the invading force, they never informed him. And as the conflict wore on, he says, U.S. commanders, even when pressed repeatedly for their views, did not ask him for more troops or disagree with the strategy.

Much of his explanation of what went wrong in the crucial first year of the occupation of Iraq stems from a prewar failure to decide how to manage the postwar political transition. Two differing approaches were debated in the run-up to the war: a Pentagon view that power should be handed over quickly to an interim Iraqi authority containing a number of Iraqi exiles, and a State Department view favoring a slower transition that would allow new leaders to emerge from within the country.

"Those key differences were never clearly or firmly resolved in the NSC," Rumsfeld writes. "Only the President could do so."

Rumsfeld blames L. Paul Bremer III, who led the first year of occupation, for pursuing a grandiose plan more in line with State's vision than the Pentagon's. Although Bremer has said he kept Pentagon officials fully informed, Rumsfeld, who was nominally Bremer's boss, now describes himself as slow to recognize Bremer's intentions.

Rumsfeld asserts that Bush exacerbated matters by allowing confusion in the chain of command and enabling Bremer to "pick and choose" which senior Washington officials to deal with. Rumsfeld quotes a memo he wrote to himself when Bremer's appointment was announced in May 2003, quietly criticizing Bush for having had lunch alone with the new envoy. "Shouldn't have done so," the memo said. The president "linked him to the White House instead of to" the Pentagon or State Department.

"There were far too many hands on the steering wheel, which, in my view, was a formula for running the truck into a ditch," Rumsfeld writes in the book.

Providing pointed critiques of other former colleagues, Rumsfeld portrays Powell as reigning over a State Department reluctant to accept Bush's political direction and intent on taking anonymous swipes at the Pentagon in the media. He chides Rice, in her initial role as national security adviser, for often papering over differences rather than presenting Bush with clear choices in cases when the Pentagon and State Department disagreed.