The Homeland Security Department is warning law-enforcement officers that Al Qaeda may be plotting to fly cargo planes from overseas into such crucial targets in the United States as nuclear plants, bridges or dams, an agency official said Friday night.
Separately, the U.S. Embassy in Saudi Arabia said it would close its diplomatic missions in that country this weekend for an undetermined period because of credible information that terrorists are about to carry out attacks.
The United States also warned that Taliban insurgents in Afghanistan may attempt to kidnap American journalists working in that country.
"The U.S. intelligence community remains concerned about Al Qaeda's interest in carrying out attacks on us overseas," said Homeland Security spokesman Brian Roehrkasse.
A Homeland Security official said the information about the cargo planes, first reported Friday by NBC News, came from a single source overseas.
"It has not yet been corroborated," the official said, speaking on condition of anonymity. "We're in the process of trying to corroborate this information."
"We also remain concerned about threats to the aviation industry and the use of cargo planes to carry out attacks on critical infrastructure," the official said.
Both the Homeland Security Department and the FBI were posting an advisory Friday night alerting state and local authorities to the threat, Roehrkasse said. The advisory also was being directed to officials responsible for security at such facilities as nuclear plants, bridges and dams, he said.
The information about possible attacks in the Middle East came from a separate source than the information about possible attacks using cargo aircraft, the official said.
Roehrkasse said the color-coded terror alert will remain at yellow, the middle level on the five-color scale indicated an elevated risk of terrorist attack.
He noted that cargo companies already have security measures in place.
Critics have said the Transportation Security Administration, the agency responsible for aviation security, hadn't done enough to make cargo planes safe. Those criticisms intensified when a New York shipping clerk packed himself in a crate and flew undetected to his parents' home in Dallas.
The government is considering regulations to plug holes in air cargo security, which has received less attention than airline passenger security since the Sept. 11, 2001, terror attacks.
Only a small percentage of cargo is checked before being shipped in cargo or passenger planes. Neither air marshals nor armed pilots are aboard cargo planes, and areas where cargo is handled at airports are not as secure as passenger terminals.
Capt. Paul Rancatore, a spokesman for the Coalition of Airline Pilots Assn. security committee, said Friday night the government treats cargo aviation differently than it treats passenger aviation.
"That, I believe, is going to lead to an incident in the future with cargo aircraft," he said.