LONDON -- Prime Minister Theresa May said Britain's threat level from terrorism has been raised to critical, meaning an attack may be imminent.

The level previously stood at the second-highest rung of "severe" for several years.

May said critical status means armed soldiers may be deployed instead of police at public events such as sports matches.

May added that raising the country's terror threat level and deploying soldiers to patrol key sites a "proportionate and sensible response" to the suicide bombing at a Manchester concert venue.

May said Tuesday, May 23, that the "callous and the cowardly" Monday attack that killed 22 people and injured another 59, many critically, justified rolling out the security measures included in a plan the government calls "Operation Temperer."

May said Salman Abadi, the suicide bomber at the Ariana Grande concert in Manchester, may have been part of a bigger network.

She said Abadi was born and raised in Britain.

May said the measures include replacing police officers who now guard "key sites" with members of the military operating under police command.

She said the move "will allow the police to significantly increase the number of armed officers on patrol in key locations." (AP)