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Subway systems may be targeted, U.S. warns

WASHINGTON (CNN) -- The U.S. Department of Transportation is alerting transit systems across the country about the ongoing possibility of terrorist attacks.

The DOT issued a "threat advisory" to transit systems Wednesday as "a reminder that this threat is still out there," spokesman Chet Lunner said.

Intelligence reports have indicated that someone might be considering attacks against subway systems in the United States, he said.

The intelligence reports are not specific as to what transit systems or cities might be targeted, nor do they carry a specific date, Lunner said.

While the intelligence reports specify subway systems, the DOT expanded the advisory to include all transit systems, he said.

The advisory does not rise to the level of a warning, he said.

The alert was put out after the DOT consulted with the FBI and the Office of Homeland Security. The FBI previously sent out notifications involving threats against the banking industry, apartment buildings and other sectors of the economy.

A spokeswoman with Washington's Metro transit system said the system had received the DOT warning Wednesday and then re-released an announcement on its public address system asking riders to report anything unusual.

Metro officials also called the FBI Anti-Terrorism Task Force for guidance. "We're already at heightened alert and we have been since September 11th," Cheryl Johnson said.