One day after a bombing claimed at least 22 lives at a concert venue in Manchester, England, Prime Minister Theresa May has announced that the U.K. is raising its terror threat level. The move, declared Tuesday evening, means members of the British military will be deployed throughout the country to supplement its police forces.
"It is a possibility we cannot ignore that there is a wider group of individuals linked to this attack," May said. "It is now concluded, on the basis of today's investigations, that the threat level should be increased for the time being — from 'severe' to 'critical.' "
She added: "This means that their assessment is not only that an attack remains highly likely, but that an attack may be imminent."
The announcement comes just hours after police identified a suspect — 22-year-old Salman Abedi — and ISIS claimed responsibility for the bombing. Greater Manchester Police also announced Tuesday that they had "arrested a 23-year-old man" in connection with Monday's bombing.
Dozens of concertgoers were also injured in the attack at the Manchester Arena at the end of an Ariana Grande show.
The BBC reports this is only the third time the U.K. has reached the highest terror threat level under its alert system — and the first since 2007.
In her brief speech Tuesday, May said the police request for military support "is part of a well-established plan known as Operation Temperer, in which both the armed forces and the police officers involved are well-trained and well-prepared to work in this kind of environment."
She laid out what to expect from the operation:
"This means that armed police officers responsible for guarding key sites will be replaced by members of the armed forces, which will allow the police to significantly increase the number of armed officers on patrol in key locations.
"You might also see military personnel deployed at certain events such as concerts and sports matches, helping the police to keep the public safe. In all circumstances, members of the armed forces who are deployed in this way will be under the command of police officers."
NPR's Bill Chappell has more on the Manchester attack — everything that we know, as of Tuesday evening — right here.
Correction: May 25, 2017 12:00 am — A previous version of this story incorrectly referred to Operation Temperer as Operation Tempora.