US issues security alert for mass transit

WASHINGTON -- US mass transit systems should remain alert against possible attacks, the Homeland Security Department said in a new warning that highlighted suspicious activity at European subway stations last fall.

A Homeland Security spokesman, Russ Knocke, said yesterday that there is no specific or credible intelligence to indicate that US transit systems are being targeted. He described the notice, sent Tuesday, as a routine reminder for transit authority operators, state security advisers and police to remain on guard.

In Chicago, a transit authority spokeswoman, Sheila Gregory, said the nation's second-largest transit system had not received any warning from Homeland Security regarding suspicious activity at European subway stations, which were not named.

Joe Pesaturo, a spokesman for the Massachusetts Bay Transportation Authority, said that the agency is already on alert: ''We have received the memo, and we are continuing to operate under the procedures we have in place for the elevated threat level."

The notice said a foreign man was arrested in November in an unnamed European city after videotaping the interior and exterior of several subway cars and stations, including trash cans and stairwells.

Three other people were later arrested for similar activity, the notice said. These incidents ''prove indications of continued terrorist interest in mass transit systems as targets, and potentially useful insights of the terrorists' surveillance techniques," the notice said.

It added: ''DHS has no credible or specific intelligence regarding active plots targeting US mass transit systems."