The New York Times has taken the unusual step of publishing an 1100-word editor’s note today admitting that were substantial problems with its coverage of Iraq and its alleged stockpile of weapons of mass destruction over the past three years.

The editors write “Information that was controversial then, and seems questionable now, was insufficiently qualified or allowed to stand unchallenged. Looking back, we wish we had been more aggressive in re-examining the claims as new evidence emerged–or failed to emerge.”

The editors goes on to say ” The problematic articles varied in authorship and subject matter, but many shared a common feature. They depended at least in part on information from a circle of Iraqi informants, defectors and exiles bent on “regime change” in Iraq, people whose credibility has come under increasing public debate in recent weeks.”

The Times outlined a series of problematic front-page articles. Although many of them were written by Judith Miller, her name is not mentioned in the editor’s note.

The paper has now admitted that it can not independently verify claims in two front page articles in October and November 2001 that Iraq operated a secret camp where Islamic terrorists were trained and produced biological weapons .

The paper also admits it was taken in by the claims of an Iraqi defector who claimed he personally worked on renovating Iraq’s secret biological, chemical and nuclear underground facilities.

The Times also cites problems in a Sept. 8, 2002 front-page article headlined “U.S. Says Hussein Intensified Quest for A-Bomb Parts.” The article was published just as the Bush administration was beginning publicly push for the invasion of Iraq.

And the paper highlights one article written after the invasion headlined “Illicit Arms Kept Till Eve of War, an Iraqi Scientist Is Said to Assert.” The article, which appeared to justify the US invasion, was based on a single unnamed Iraqi informant who claimed Iraq had sent its weapons of mass of destruction to Syria before the invasion and that he had personal proof that Iraq was cooperating with Al Qaeda. The Times now admits it never followed up on the veracity of this source or attempted to verify his claims.

While all of the articles cited as problematic by the Times appeared on page one of the paper, today’s editor note appears buried in the paper on page A 10–unlike other major editor notes that have appeared on A 2.