Armed police are to travel on the Tube network following the recent bomb alert at a station close to the O2 entertainment venue.
Firearms patrols, which are routinely deployed at mainline train stations, will use the Tube to travel between jobs.
Armed officers were deployed on the London Underground following the 7/7 tube bombings in 2005, but that measure was only temporary.
British Transport Police said seeing armed officers on the Tube on a daily basis should reassure the public that they would be able to respond to any threats.
The move was announced after a suspect package was spotted on a Jubilee Line underground train last week by a member of the public.
The train was stopped at North Greenwich station, close to the O2, where police carried out a controlled explosion of the package.
London student, Damon Smith, has been arrested in connection with the incident and remains in custody.
