US Airports Warned of Terror Attack Rehearsals

Airport security teams have been warned to be on the lookout for terrorists attempting to carry explosive components onto planes as part of a dry run for future attacks, the AP reports. The TSA issued the alert last week after four passengers were caught with clay, wire, pipes, switches and other materials officials said may be "improvised explosive device components." 

Material was seized at airports in San Diego, Milwaukee, Houston and Baltimore. Passengers' explanations were suspicious, and some of the passengers are still under investigation. A 13-point unclassified bulletin warning of the threat was leaked to NBC News and CNN, but Homeland Security officials downplayed the danger. "We do these things all the time," said one. (More TSA stories.)