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The claim Iraq could deploy chemical and biological weapons within 45 minutes should only have been used in a government dossier with more explanation, the Butler report says.
The dossier was used to justify sending UK troops to war in Iraq
Former Cabinet Secretary Lord Butler's team said the claim - included in a September 2002 dossier on Iraq - had been potentially
misleading because it had not explained it referred to
The Joint Intelligence Committee "should not" have included it without stating exactly to what it referred.
And the fact it had been mentioned four times in the September 2002 dossier had led to suspicions it had been included for "its eye-catching character".
"The report Saddam could deploy chemical and biological
weapons within 45 minutes in the form which it appeared... in the
government dossier was unclear," Lord Butler said.
"The validity of the reporting chain which
produced" the claim had "become doubtful" since the war, he added.
Lord Butler called the "unsubstantiated" claim an "uncharacteristically
poor piece of assessment", but said it had been an "exception".
The report says: "Validation of human intelligence sources after war has thrown doubt on a high proportion of those sources and of
their reports; and hence on the quality of the intelligence
assessments received by ministers and officials in the period from
summer 2002 to the outbreak of hostilities."
The intelligence report about the claim was "vague and ambiguous", said Lord Butler.
Forty-five minutes was the kind of time period a military expert might expect - in fact, it was somewhat longer than a well-organised military unit might hope for.
It seemed to confirm to those who thought it referred to battlefield weapons that Iraq had both forward-deployed chemical and biological munitions.
The report says the dossier should have made clear the exact nature of the weapons, the agents involved and the context of their use was not clear.