London [U.K.], June 7 (ANI): London attack ringleader Khuram Butt was identified as a major potential threat, which led to an investigation starting in 2015. "The British police and the MI5 began investigating Butt intensively as part of a major drive to dismantle and destabilise al-Muhajiroun, a grouping of extremists in the U.K. supportive of the ISIS," U.K. counter-terrorism officials told CNN. The investigation into Butt involved a "full package" of investigatory measures. As soon as the British extremists began to flock to Syria to join the ISIS' newly declared caliphate in 2014, counter-terrorism officials moved more aggressively to take...