So, that's what was going on in Powell's intercepts.

One of the great mysteries of the Iraq war has been solved. The puzzler goes back to then-Secretary of State Colin Powell's now-notorious briefing before the U.N. Security Council on Feb. 5, 2003, the one where he laid out the best case he could muster for the claim that Saddam had weapons of mass destruction. In retrospect, the case was a shambles; even at the time, much of it seemed dubious. But there was one very persuasive section—playbacks of intercepted phone conversations between Iraqi military officers that suggested they were hiding WMD from the U.N. inspectors.

The first of these tapes, from Nov. 26, 2002, caught an Iraqi colonel and general talking about a suspected weapons site that the inspectors would be visiting the following day. The general said: "I'll come see you in the morning. I'm worried you could have something left." The colonel replied, "We evacuated everything. We don't have anything left."

The second of these tapes, from Jan. 30, 2003, caught one commander of the 2^nd Republican Guard Corps telling another: "Write this down. … Remove the expression 'nerve agent' wherever it comes up in the wireless instructions."

Powell played these tapes as Exhibit A in his presentation, and for good reason. They appeared to reveal that the Iraqis still possessed illegal chemical or biological agents and that they were deliberately hiding the materials from inspectors.

In a Slate column at the time, I called the tapes a "smoking gun." Six months later—after "major combat operations" had ceased, the U.S. military inspectors had failed to turn up any WMD, and the once-dubious parts of Powell's briefing had been proved conclusively false—I wrote that those tape intercepts were still "puzzling." Were the tapes fabrications, like the forged "yellowcake" documents? Were the translations accurate? Were these officers really talking about what Powell said they were talking about? Were they staging the conversation to make U.S. officials listening in believe Saddam had WMD (on the premise that the possession of such weapons might deter the United States from invading)?

Now, three years after the fact, a plausible answer has emerged. In the middle of a big article in Sunday's New York Times, Michael Gordon and Gen. Bernard Trainor report that the officers were talking about removing not weapons, agents, or munitions, but rather "residue from old unconventional weapons programs" dating back to before the 1991 Gulf War.

Gordon and Trainor (whose story is an excerpt from their new book, due out this week, Cobra II: The Inside Story of the Invasion and Occupation of Iraq) gleaned this conclusion from a classified report, prepared by the U.S. military's Joint Forces Command, on Iraqi views of the war. The JFC analysts who worked on the study interrogated more than 110 Iraqi officials and officers and perused over 600 captured Iraqi documents. A declassified 8,500-word excerpt of this report appears in a forthcoming issue of Foreign Affairs, whose editors rushed it online late Sunday in reaction to the Times' publication.

As the Times piece put it:

To ensure that Iraq would pass scrutiny by United Nations arms inspectors, Mr. Hussein ordered that they be given the access that they wanted. And he ordered a crash effort to scrub the country so the inspectors would not discover any vestiges of old unconventional weapons, no small concern in a nation that had once amassed an arsenal of chemical weapons, biological agents and Scud missiles.

The tragic irony is spelled out in Foreign Affairs' excerpt of the report: