New York City tightened its transit security on Tuesday as the result of the deadly bombings of Mumbai's commuter rail network.
The New York Police Department said it was increasing the number of random bag searches and putting hundreds of extra officers in the subways during the evening rush hour.
The department said the measures were precautionary, and there had been no specific threats to New York.
The city began random bag searches a year ago in response to the mass transit bombings in London. NYPD officials have refused to say how many bags police have searched in the past year, or specify where and when they do it. They claim that by making deployment unpredictable, they can keep would-be bombers off-balance.
The city's 468 subway stations serve an average 4.