An airline passenger hands over a can of shaving cream to tw

UNITED STATES - AUGUST 10: An airline passenger hands over a can of shaving cream to two airport workers screening for liquids at Dulles International Airport outside Washington, D.C., Thursday, August 10, 2006. The U.S. raised its terror alert to the highest level for flights from the U.K. after the discovery of a ``well-advanced plan,'' suggestive of al-Qaeda, to use electronic devices or liquid explosives to blow up jetliners in midair, officials said. (Photo by Jay Mallin/Bloomberg via Getty Images)