Nick Hopkins and Ewen MacAskill write:
Britain has become more vulnerable to terrorist attacks because “frustrated travellers” are finding it more difficult to get to Syria and are being urged by different extremist groups to commit atrocities in the UK.
The return of some British fighters from Syria has added to a complex picture, which means the UK’s counter-terrorism agencies are feeling heat from all sides, intelligence sources said.
“There is pressure on the counter-extremism strategy because of the confluence of frustrated travellers who would go to Syria if they could but are stuck here, and returnees,” said one Whitehall source.
“Both Isis (Islamic State) and al-Qaida are calling for these travellers to stay at home and attack in the west instead. The risk seems far greater now. The risk is changing.”
The police and intelligence services are seeking to establish the motive of the Manchester killer, Salman Abedi, and whether he was working alone or part of a wider network. Although Isis claimed responsibility, the police have not found any evidence to support this.