In the wake of attempted terror attacks on French trains last year, France is adding armed plainclothes guards who will ride trains in pairs and function similarly to the 'unseen' sky marshals who ride on many U.S. airline flights.
The program originated after passengers were able to disarm a man who attempted to shoot up a Paris-Amsterdam train last year. The guards will ride the trains incognito and unannounced, but will have authority to ask passengers for ID, or to check luggage at stations.
The number of guards has not been announced, but the Paris newspaper Le Figaro says there could be as many as 3,000. Other measures coming into place include more security checks, including scanners, and more surveillance cameras.