At the same time, terrorists have learned that the seemingly benign shell of a vehicle can allow them to conceal explosives in particularly effective settings.

Senior officers said that procedures would be tightened to require occupants of cars to get out and open trunks, hoods or other parts of cars or trucks that could conceal explosives.

Another man was arrested several blocks from the site of the shootout and was forced to strip naked by police who feared he might have concealed explosives.

A senior Air Force official involved in planning missions over Iraq said surveillance planes, by their mere presence, reduced insurgents' ability to conceal explosives.

There were reports that men disguised as repairmen had concealed weapons and explosives in the school sometime during July 2004, but this was later officially refuted.

New FBI documents were also released revealing new details about Posada's many terrorist plots, including concealing high explosives in shoes and shampoo bottles.

Troops learn to watch for rough patches in a road where bombs have been buried, to avoid dead animals on streets that may conceal explosives and to drive at high speeds through potential ambushes.

The bomber will conceal explosives on and around their person, commonly using a vest and will use a timer or some other trigger to detonate the explosives.

In December 2010 airport security in Canada and the US began subjecting insulated beverage containers to greater scrutiny because of the possibility that they could conceal explosives.

By concealing explosives on a willing carrier, a faction can smuggle death int-o densely populated areas or close to key targets.