Isolated Incidents......"snort"

Today's Bumper Sticker

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 on July 20 by the Transportation Security Administration 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, cell phone components and dense clay-like 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."

The four seizures were described this way:

• San Diego, July 7. A U.S. person — either a citizen or a foreigner legally here — 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 carryon 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 clay-like 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 cellular phone charger.