The Manchester Arena bomber was a ‘subject of interest’ and the attack could have been stopped, a new review says.
David Anderson QC, the review’s author, said it was conceivable Salman Abedi’s attack could have been prevented if cards had fallen differently.
But he said it was ‘unknowable’ whether reopening investigations into Abedi would have changed his plans, adding: ‘MI5 assesses that it would not’.
Greater Manchester Police said its officers would ‘never stop learning’.
After the Manchester bombing and three terror attacks in London this year, counter terror police and MI5 conducted internal reviews, and Anderson carried out an independent assessment of their findings.
The report shows that: Salman Abedi has been a ‘Subject of Interest’ for MI5 between January and July 2014, and then again in October 2015; on two occasions in the months before Abedi killed 22 people, MI5 received intelligence, but its significance was not fully appreciated at the time, and, in hindsight, was ‘highly relevant’ to the planned attack; and there was no security service port alert against Salman Abedi, so he was not questioned at the border when he returned to the UK from Libya four days before the attack.
The reviews also showed the two other attackers who had been on MI5’s radar were Khuram Butt, the leader of the London Bridge and Borough Market attack, and Khalid Masood who targeted Westminster Bridge.
Butt had been identified by MI5 and the police as someone who wanted to attack the UK two years prior.
He was still a ‘live subject of interest’ who was under investigation at the time of the attack, though more for his intention to travel to Syria and for radicalising others.
He was also the main target of ‘Operation Hawthorn’, but this was suspended twice because of a lack of resources after the Bataclan attack in Paris and the Westminster Bridge attack.
Operation Hawthorn had resumed and was running on the day Butt attacked.
Anderson, former independent reviewer of terror legislation, said: “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.
"In particular, MI5 and the police have identified the need to use data more effectively, to share knowledge more widely, to improve their own collaboration and to assess and investigate terrorist threats on a uniform basis, whatever the ideology that inspires them.”