American forces in Iraq are doing tests on trailer that matches the description of a mobile biological weapons lab given by various sources including defectors, the Pentagon said Wednesday.
..
Cambone said more testing will be required, noting that the surface of it had been washed with a caustic material and it likely would have to be dismantled before testing can be done on hard-to-reach surfaces.

It is painted a military color scheme, was found on a transporter normally used for tanks and - as an Iraqi defector has described Iraq's mobile labs - contains a fermentor and a system to capture exhaust gases, Cambone said.
...
Lt. Gen. William S. Wallace, commander of the Army's V Corps, told a press conference the reason Saddam didn't use unconventional weapons against invading forces may be that these weapons were buried too well to retrieve before the fast coalition dash to Baghdad.
...
On several occasions, troops have found substances they said tested positive as nerve agents or other chemical weapons materials, only to learn from more sophisticated testing that they were crop pesticides, explosives and so on.

The defense official said that he and others "feel good" about the prospect this time that they have found good evidence of an unconventional weapons program.

But they are being careful to cover all bases. He noted that many questions will be asked if it is announced as the evidence - including "chain of custody" information on who has handled the truck and whether it might have been tampered with.

» U.S. Says It Has Suspected Iraq Arms Lab (washingtonpost.com)