TSA warns of possible dry runs for terror attacks

WASHINGTON — Airport security officers around the nation have been alerted by federal officials to look out for terrorists practicing to carry explosive components onto aircraft, based on four curious seizures at airports since last September.

The unclassified alert was distributed July 20 by the Transportation Security Administration (TSA) to federal air marshals, its own transportation security officers and other law-enforcement agencies.

The seizures at airports in San Diego, Milwaukee, Houston and Baltimore included "wires, switches, pipes or tubes, cellphone components and dense claylike substances," including block cheese, the bulletin said. "The unusual nature and increase in number of these improvised items raise concern."

Security officers were urged to keep an eye out for "ordinary items that look like improvised explosive device components."

Homeland Security spokesman Russ Knocke described the notice as a routine informational bulletin for TSA workers, airport employees and law-enforcement officials.

"There is no credible, specific threat here," TSA spokeswoman Ellen Howe said Tuesday. "Don't panic. We do these things all the time."

The bulletin said the passengers carrying the suspicious items seized since September included men and women and an initial investigation had not linked them with criminal or terrorist organizations. But it added that most of their explanations for carrying the items were suspicious and some were still under investigation.

The four seizures were described this way:

• San Diego, July 7. A U.S. person checked baggage containing two ice packs covered in duct tape. The ice packs had clay inside them rather than the normal blue gel.

• Milwaukee, June 4. A U.S. person's carry-on baggage contained wire coil wrapped around a possible initiator, an electrical switch, batteries, three tubes and two blocks of cheese. The bulletin said block cheese has a consistency similar to some explosives.

• Houston, Nov. 8, 2006. A U.S. person's checked baggage contained a plastic bag with a 9-volt battery, wires, a block of brown, claylike minerals and pipes.

• Baltimore, Sept. 16, 2006. A couple's checked baggage contained a plastic bag with a block of processed cheese taped to another plastic bag holding a cellphone charger.