Shortly after UK police identified 22-year-old Salman Abedi as the suspected suicide bomber who detonated bombs on Monday evening at the Ariana Grande concert in Manchester which killed 22 people, Prime Minister Theresa May announced that the UK has raised its threat level to "critical".
This is the highest level for the first time in a decade. The last occasions were in August 2006 and June 2007. Both times, the assessment was lowered after a few days.