That includes bombs built with chemical triggers that avoid use of metallic components and powerful explosives such as PETN, or pentaerythritol tetranitrate, a white powder that can deliver a powerful blast.

Still, to ramp up the game's realism, "Warfighter" creators mimicked real-world weaponry and centered the plot on the ripped-from-the-headlines threat of an industrial explosive known as PETN, or pentaerythritol tetranitrate, the same material used in 2001 by convicted shoe bomber Richard Reid when he tried to destroy a trans-Atlantic flight.

A preliminary analysis suggested a nitrate-based explosive, with traces of pentaerythritol tetranitrate, a plastic explosive, had been used in the attack.

PETN, or pentaerythritol tetranitrate, is hard to detect.

The materials included Pentaerythritol tetranitrate, or PETN, the explosive used in the 2001 airliner shoe-bombing attempt as well as airplane cargo bombs discovered last month.