The latest Metropolitan Police tactic, dubbed Project Servator, will involve specialist police officers deployed in Wandsworth and Lambeth boroughs of south London.
The Met stressed the new tactic was not in response to a specific threat and will be rolled out across other parts of London in coming months.
"Keeping Londoners safe is the Mayor's top priority and we know our emergency services do a great job every single day protecting our city.
"However, we cannot be complacent, which is why it is good to see the Met rolling out Project Servator to help deter and detect crime in our city's busiest areas," said Sophie Linden, London's Deputy Mayor for Policing and Crime.
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Project Servator was developed, tested and refined over a five-year period by experts at the UK's Centre for Protection of National Infrastructure (CPNI) and is already used by a number of forces, including City of London Police and British Transport Police, to disrupt those planning to carry out crimes from shoplifting to terrorist attack planning.
Uniformed police patrols will be joined by plain clothes officers who have been trained to spot tell-tale signs that a person may be carrying out hostile reconnaissance or engaging in other criminal activity.
"Wandsworth is a vibrant borough with some of the busiest transport hubs in the country and tens of thousands of commuters passing through daily," Borough commander for Wandsworth, Chief Superintendent Richard Smith, said.
"If you see something suspicious, report it. If you see police officers, take a moment to talk with them and find out how you can play you part."
"Lambeth is home to many diverse communities, iconic sites and busy town centres. The launch of Project Servator in Lambeth will help ensure that we continue to protect those communities and locations from terrorism and other crime," Borough Commander for Lambeth, Chief Superintendent Richard Wood, said.