The plan was activated for the first time on 23 May 2017 following the Manchester Arena bombing . Prime Minister Theresa May announced that the police had asked for military support and the request had been approved by Sir Michael Fallon , the Secretary of State for Defence . The operation remained in force until the end of the bank holiday weekend , despite the threat level being reduced from critical to severe on 27 May
Manchester Arena bombing
Manchester Arena bombing
Operation Temperer