A new concern for air travelers: Islamic terrorists have conducted “dry runs” of operations involving the assembly of bombs in mid-flight. (Hat tip: J.D.)

Officials in Saudi Arabia and elsewhere are believed to have warned that at least 12 dry runs may have been completed and to have said that the terrorists are aiming to try out their plans on flights around the Mediterranean and the Middle East before attempting to bomb a transatlantic route, where security precautions are now very tight. Militants know that individual components are far easier to smuggle through airport security than an assembled bomb.

In May 2002 nearly 100 grammes of pentrite, a plastic explosive used by the alleged shoe bomber Richard Reid, was found hidden in the armrest of a Moroccan jet when it landed in Metz, France. At the time, investigators said they thought it had been put there as a warning. Now French officials suspect the explosives were placed on the jet as a trial of the new tactics. Though some investigators fear they may be the victim of deliberate ‘disinformation’, officials say that they cannot risk ignoring the warnings.