President Barack Obama observed: “ISIL [Daesh] is a direct outgrowth of Al Qaeda in Iraq that grew out of our invasion — which is an example of unintended consequences — which is why we should generally aim before we shoot.”

Many of us looking at the horror of the Iraq war, waged by the US and the UK against the regime of president Saddam Hussein, in which 200,000 civilians died and for which a total of $800 billion were spent, need little to be persuaded that there was a Machiavellian plot to find an excuse to make war.

Yet, there are many in the circles of power in Washington who believe the US should shoot on sight and kill whenever danger is thought to have appeared — in Iraq, Syria, Libya and, before that, in Vietnam.

The so-called “justification” for going to war in Iraq 13 years ago was based on a 93-page classified CIA document that allegedly contained “specific information” on Saddam’s weapons of mass destruction (WMD) programmes and his close links with Al Qaeda.

The document has now been declassified thanks to the work of investigative journalist John Greenewald. His findings have just been published in the online magazine, VICE.

The document, before published with a large number of deletions, is available for everyone to read in its entirety.

It reveals that there was absolutely no justification for the war. It reveals that there was “no operational tie between Saddam Hussein and Al Qaeda” and no WMD programmes.

President George W. Bush’s secretary of defence, Donald Rumsfeld, claimed that the US had “bulletproof evidence” linking Saddam to the terrorist group.

“We do have solid evidence of the presence in Iraq of Al Qaeda members. We have what we consider to be very reliable reporting of senior-level contacts going back a decade, and of possible chemical and biological-agent training”.

The Central Intelligence Agency’s (CIA) National Intelligence Estimate report takes a very different line. The document observes that its information about a working relationship between Al Qaeda and Saddam was based on “sources of varying reliability”.

“As with much of the information on the overall relationship, we do not know to what extent Baghdad may be actively complicit in this use of its territory for safe haven and transit.”

A report issued last December by the high-powered RAND Corporation, which employs some of the best analysts in the US, titled “Blinders, Blunders and Wars”, said the CIA report “contained several qualifiers that were dropped. As the draft went up the intelligence chain of command the conclusions were treated increasingly definitively”.

One example is that the CIA report concluded that Iraq “probably has renovated a vaccine production plant to manufacture biological weapons, but we are unable to determine whether biological weapons research has resumed”.

The report also said that Saddam did not have “sufficient material” to manufacture nuclear weapons. But on October 7, 2002, in a speech in Cincinnati, Ohio, Bush said that Iraq “possesses and produces chemical and biological weapons” and “the evidence indicates that Iraq is reconstituting its nuclear weapons programme”.

As for Rumsfeld’s claim “solid evidence of the presence in Iraq of Al Qaeda members”, the CIA report concluded that it was not at all clear that Saddam “had even been aware of the relationship, if in fact there were one”.

Congress’ later investigation concluded that the intelligence community based its claims on a single source.

Paul Pillar, now a visiting professor at Georgetown University and before that in charge of coordinating the intelligence community’s assessments on Iraq, told VICE that the bio-weapons claims were based on unreliable reporting by sources such as Ahmad Chalabi, the former head of the Iraqi National Congress, an opposition group.

“There was an insufficient scepticism about some of the source material,” Pillar said.

“I think there should have been agnosticism expressed in the main judgements.”

Pillar went on to say Bush and Rumsfeld “had already made the decision to go to war in Iraq, so the CIA report didn’t influence their decision”. But they used their misleading interpretations of it to convince public opinion that war was necessary. (The British ambassador at the time wrote in his book that he had told the British prime minister, Tony Blair, this. Yet, Blair went on telling the public that evidence of malfeasance was still being gathered.)

The RAND study also concluded that the report was wrong on mobile biological labs, uranium ore purchases from Niger and Iraq building rocket delivery systems for WMD.

Yes, aim before you shoot. And do not tell such terrible lies.