A terrorist attack on a Manchester concert venue that left 22 people dead could have been averted if security officials responded differently to intelligence about the suicide bomber in the months before the attack, the UK government said on Tuesday.
The finding follows a review of the handling of intelligence by police and security officials over four attacks - three in London and one in the northern city of Manchester - from March to June that left a total of 36 people dead.
“It is conceivable that the Manchester attack in particular might have been averted had the cards fallen differently,” according to an independent review by barrister David Anderson QC published on Tuesday.
The review found that on two separate occasions, the domestic security agency MI5 received information “whose significance was not fully appreciated at the time”, said Mr Anderson.
The undisclosed information received about the suicide bomber, Salman Abedi, 22, was assessed to be related to criminality and not terrorism. “In retrospect, the intelligence can be seen to have been highly relevant to the planned attack,” Mr Anderson concluded.
Had its significant been realised, an investigation would have been opened. “It is unknowable whether such an investigation would have allowed Abedi’s plans to be pre-empted and thwarted: MI5 assesses that it would not,” he said.
The review also revealed that Abedi was one of a small group from 20,000 former suspects of interest from across the UK who could have faced closer scrutiny following the analysis of data held by British authorities. A meeting was due to be held about the group on May 31 - nine days after the attack on the Manchester Arena.
The report also found that MI5 missed an opportunity to place him on a list following his visit to Libya in April 2017.
His return to the country shortly before the attack would have triggered an alert and allowed him to be questioned at the airport under anti-terrorism legislation.
Abedi, born in Britain of Libyan parents, filled a rucksack with metal and blew himself up in the foyer as families filed out of a concert by US pop star Ariana Grande. Of the 22 who were killed, more than a third of them were girls.
His younger brother Hashem remains detained in Libya while the UK seeks his extradition to face trial for his alleged role in the attacks.
The inquiry was an attempt to learn lessons from the most deadly attacks on on British soil since the coordinated attack on the London transport network in 2005 which left 52 people dead.
Three of the attacks - on Manchester, London Bridge and at Westminster in March - were Islamist terrorist attacks. A fourth involved a Briton driving a van into a crowd of worshippers outside a mosque in north London. The driver has been charged with murder.
The report disclosed that three terrorists involved in the four attacks had at some point been on the authorities’ radar. Khuram Butt, who led the three-strong gang who were all shot dead by police during a van and knife attack on London Bridge in June, was the only “active subject of interest” and had been from mid-2015.
The report says material relating to Butt received in the two weeks prior to the attack added little to the intelligence picture and did not identify activity that led up to the attack.
Amber Rudd, the UK’s home secretary, told lawmakers that that MI5 and counter-terrorist high commanded concluded “they could not, quote, 'find any key moments where different decisions would have made it likely that they could have stopped any of the attacks'."
She said that the intelligence agencies had disrupted 22 Islamist terrorist plots since the murder of Lee Rigby, a soldier, in May 2013, including nine since the Westminster attack in March.
Mr Anderson’s assessment of 1,150 pages of internal assessments examining the actions of police and MI5 concluded there was “no cause for despair” but made 126 recommendations to try to prevent further attacks.
"The excellent recent record of MI5 and the police in defending the UK from terrorist attack came to a brutal end this year at Westminster, Manchester Arena, London Bridge and Finsbury Park,” said Mr Anderson, a former anti-terror laws watchdog.
"Despite elevated threat levels, the fundamentals are sound and the great majority of attacks continue to be thwarted. But the shock of these incidents has prompted intensive reflection and a commitment to significant change."
The leader of Manchester city council said the review’s findings would be “painful for the grieving families and others injured and traumatised” by the events at the Arena on May 22.
“It is recognised that lessons need to be learned from the attacks in Manchester and London… and I am sure that there is a real determination among the relevant services to ensure that it does," said Richard Leese.