HPMs are man-made lightning bolts crammed into cruise missiles. They could be key weapons for targeting Saddam Hussein's stockpiles of biological and chemical weapons. HPMs fry the sophisticated computers and electronic gear necessary to produce, protect, store and deliver such agents. The powerful electromagnetic pulses can travel into deeply buried bunkers through ventilation shafts, plumbing and antennas. But unlike conventional explosives, they won't spew deadly agents into the air, where they could poison Iraqi civilians or advancing U.S. troops.