The FBI has warned law enforcement agencies that Al Qaeda cells might use fuel trucks as weapons to attack Los Angeles, New York and Chicago, but officials stressed Thursday that the warning was based on uncorroborated intelligence.
The warning was distributed Tuesday via a computer network by FBI officials in Los Angeles to law enforcement agencies primarily in California, said FBI spokeswoman Laura Eimiller.
Though intelligence bulletins usually describe how reliable the information is, this one carried no such statement.
The bulletin warned police that terrorists could use fuel tankers in assaults on the three cities. The warning has not been substantiated, according to two law enforcement officials who spoke on condition of anonymity because of the sensitivity of the situation.
The intelligence originated from FBI headquarters in Washington. It was not immediately clear why the bulletin was sent without details on its reliability.
Eimiller noted that FBI officials often notify police of possible threats, regardless of how accurate the information might be.
"Information at all levels is shared with law enforcement," she said.
News of the warning came as Santa Monica police stepped up patrols after receiving a report that three people had been seen videotaping the popular pier.
But FBI officials Thursday downplayed the seriousness of a possible terrorist threat based on the videotaping activity, although the agency is assisting Santa Monica police.