WASHINGTON (Reuters) - The Defense Department on Tuesday began issuing "escape masks" to nearly 25,000 workers at the Pentagon and training them in use of the devices in case of chemical or biological attack. The department has purchased 80,000 of the head-covering masks at a cost of about $150 each to protect employees and visitors to its headquarters and at more than 40 other buildings leased by the military in the nation's capital. The move, sparked by hijacked airliner attacks on America in September 2001 and accelerated by the prospect of terror strikes using deadly gases or toxins, began with...