Hugh Pickens writes "As you weave through interstate traffic, you're unlikely to notice a plain-looking Peterbilt tractor-trailer or have any idea that inside the cab an armed federal agent operates a host of electronic countermeasures to keep outsiders from accessing his heavily armored cargo: a nuclear warhead. Adam Weinstein writes that the Office of Secure Transportation (OST) employs nearly 600 couriers to move bombs, weapon components, radioactive metals for research, and fuel for Navy ships and submarines between a variety of labs, reactors and military bases. Hiding nukes in plain sight and rolling them through major metropolitan centers raises a slew of security and environmental concerns, from theft to terrorist attack to radioactive spills. 'Any time you put nuclear weapons and materials on the highway, you create security risks,' says Tom Clements, a nuclear security watchdog for Friends of the Earth. For security, cabs are fitted with custom composite armor and lightweight armored glass, a redundant communications system that links the convoys to a monitoring center in Albuquerque, and the driver has the ability to disable the truck so it can't be moved or opened. The OST hires military veterans, particularly ex-special-operations forces (PDF), who are trained in close-quarters battle, tactical shooting, physical fitness, and shifting smoothly through the gears of a tractor-trailer. But accidents happen. In 1996, a driver flipped his trailer on a two-lane Nebraska hill road after a freak ice storm, sending authorities scrambling to secure its payload of two nuclear bombs; and in 2003, two trucks operated by private contractors had rollover accidents in Montana and Tennessee while hauling uranium hexafluoride, a compound used to enrich reactor and bomb fuel."