Armed troops will be deployed to guard key locations in London including Buckingham Palace, Downing Street, Westminster and embassies.
Soldiers will replace armed police at many sites after security experts warned the Government that another terrorist attack could be imminent.
The decision taken at a meeting of the Government's emergency Cobra committee will mean soldiers will play a key role in protecting civilians and free up armed police officers to help fight the terror threat.
We will do all we can to protect the capital that we serve at this unsettling time. All our work is designed to make our city as hostile an environment as possible for terrorists to plan and operate.
– COMMANDER JANE CONNORS, MET POLICE