The top policy adviser to Defense Secretary Donald H. Rumsfeld (search) says the Bush administration erred by building its public case for war against Saddam Hussein mainly on the claim that he possessed banned weapons.

The comment by Douglas J. Feith (search), in an interview with The Associated Press, is a rare admission of error about Iraq by a senior administration official. Feith, who is leaving after four years as the undersecretary of defense for policy, said he remains convinced that President Bush was correct in deciding that war against Iraq was necessary.

"I don't think there is any question that we as an administration, instead of giving proper emphasis to all major elements of the rationale for war, overemphasized the WMD aspect," he said, using the abbreviation for weapons of mass destruction.

The administration claimed the now-deposed Iraqi president possessed mass-killing chemical and biological weapons at the time of the March 2003 invasion and cited them most prominently as justification for attacking.

No such weapons have been found. In March, a bipartisan presidential commission said U.S. spy agencies were "dead wrong" in most of their prewar assessments about Iraq's weapons of mass destruction.

One of the architects of the administration's strategy for the War on Terror, Feith strongly defended the decision to invade Iraq.

"It would have been better had we done a better job of communicating in all of its breadth the strategic rationale for the war," Feith said in an hour-long interview this week at his home in suburban Washington.

The broader rationale, Feith said, included the danger posed by Iraq's potential to resume building chemical, biological and possibly nuclear weapons — know-how that the Iraqi regime developed before the 1991 Gulf War.

In his report to Congress on a CIA-led postwar search for Iraqi weapons of mass destruction, U.S. arms inspector Charles Duelfer (search) said none could be found and there was no evidence Saddam produced any after 1991. But Duelfer also said it was clear that Saddam hoped to revive his weapons programs if U.N. sanctions were lifted.

"Our intelligence community made, apparently, an error, as to the stockpiles" of weapons it assured President Bush existed in 2003, Feith said. Thus that part of the administration's argument for why war was necessary was overdone, he said, adding, "Anything we said at all about stockpiles was overemphasis, given that we didn't find them."

Feith has been accused by critics of having manipulated intelligence on Iraq to push the case for war, an accusation he vehemently denies. His chief critic in Congress on this point is Sen. Carl Levin (search), D-Mich., who is delaying Senate confirmation of Feith's replacement, Eric Edelman, a former ambassador to Turkey, by demanding the Pentagon produce more documents on the intelligence controversy.

Feith said he is irritated by the assertions of administration critics that the absence of WMD stockpiles in Iraq negates the rationale for going to war. They ignore the broader reasoning, he said, which included the dangers posed by Saddam's record of aggression against Kuwait, hostility toward the United States, a "rhetorical and financial support" for terrorism and a weakening of the world's resolve to contain his ambitions.

"One could fault the administration on the presentation of the rationale, but that is different from saying the rationale was actually extremely narrow and invalidated by the disclosure of the error" on WMD stockpiles, he said.

Another element of the administration's reasoning was a belief, still held, that if the tyrannical regime in Baghdad could be replaced with democratic institutions, it could have a beneficial effect in transforming the politics of the Middle East. That alone, however, was not a sufficient reason to go to war, Feith said.

"Had Saddam Hussein not been a supporter of terrorism and a guy who developed and used WMD, I don't think that simply saying he's a tyrant and we have a chance to replace a tyrant would have motivated the war," he said.

Feith, who served in the White House and at the Pentagon during the administration of President Reagan, said one of his most important contributions during his four years working for Rumsfeld was helping break down communication and cultural barriers between Pentagon civilian and military officials.

By working closely with Gen. Peter Pace, the vice chairman of the Joint Chiefs of Staff, and exposing scores of staff members to their example of cooperation and collegiality, the "great divide" between the civilian and military policy organizations and their "clash of memoranda" has been largely overcome, Feith said.