The Manchester bombing: unknown unknowns and “hindsight bias”

Yet headlines like these are misleading, neglecting the nuance in Anderson’s report that the decision to ignore or misinterpret the intelligence on Abedi was “understandable” in the circumstances, overlooking the complex nature of counter-terror investigations. So, could the Manchester bombing really have been prevented?

Unknown unknowns
For the security services, piecing together the intelligence jigsaw is a difficult process. Post-mortem reviews often suffer from hindsight bias. Complex issues become easy to interpret. Intelligence previously considered irrelevant, becomes suddenly important. Knowing the end result often provides clarity where there was none at the time.

“Hindsight can sometimes see the past clearly – with 20/20 vision,” concludes the 9/11 Commission report. In her classic study of the attack on Pearl Harbor, intelligence academic Roberta Wohlstetter found it “easier after the event to sort the relevant from the irrelevant signals.” Intelligence before an event is “obscure and pregnant with conflicting” messages.

Intelligence agencies are far from the all-seeing and all-knowing entities of popular imagination. The very nature of intelligence means that the information available to the security services is often incomplete. Remember this classic bit of intelligence speakfrom U.S. Defense Secretary Donald Rumsfeld in February 2002? “We know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns – the ones we don’t know we don’t know.”

Lord Butler’s review of intelligence on Iraqi Weapons of Mass Destruction (WMD) also makes it clear that “intelligence seldom acquires the full story.” When collected, the information is “sporadic and patchy”. In these circumstances, intelligence gaps are to be expected.

Talk of failure also overlooks the growing tempo of counter-terror operations in the U.K. On Tuesday, MI5’s Director General Andrew Parker told ministers that his service had prevented “nine terrorist attacks” in the previous 12 months. Since the 2013 killing of Fusilier Lee Rigby, 22 attacks had been foiled. MI5 and counter-terrorism police continue to be inundated with potential threats.

Amber Rudd revealed to parliament there were over 500 live operations – up by a third since the start of the year – with a further 3,000 extremists categorized as “subjects of interest”. A further 20,000 individuals have been investigated and may pose a threat in future. The security services have to prioritize threats – sometimes with tragic results.

Intelligence failure?
In 2004, MI5 surveillance of the ringleaders of a fertilizer bomb plot, known as Operation Crevice, picked up two of the future July 7 suicide bombers – Mohammed Sidique Khan and Shehzad Tanweer. At the time, both were marginal figures. Continued surveillance of the Crevice cell led to successful prosecutions of others but Khan and Tanweer remained off MI5’s radar until the 7/7 attacks. The pair killed 52 commuters on the London transport network with their co-conspirators. Questions were again asked as to how two terrorists fell through the gaps of an inquiry and went on to kill. But hindsight made it easier to connect the dots that MI5 had missed.

Anderson’s report highlights that problems continue with the security services’ strategies for dealing with “low level” subjects of interest that may suddenly pose a threat, a concern raised by the Parliamentary Intelligence and Security Committee in 2013. But claims that the Manchester Arena bombing could have been stopped are too simplistic.

The report acknowledges the “inherent uncertainty” of whether more could have been done, while, on the balance of probability, a “successful pre-emption… would have been unlikely.” Abedi could have been stopped, for Anderson, had “the cards fallen differently.” In reality, they rarely do. Simplistic headlines that the attack could have been prevented fail to understand the complicated situation facing the security services and do little to bolster public confidence in the U.K.’s counter-terror effort.

Dan Lomas is Program Leader, M.A. Intelligence and Security Studies, University of Salford. This article is published courtesy of The Conversation (under Creative Commons-Attribution / No derivative).