Just 1.5 miles off the coast of Sheerness, within the busy shipping lanes of the Thames Estuary, the rusted masts of a World War II Liberty ship protrude ominously from the water. This is the wreck of the SS Richard Montgomery, a vessel that sank in 1944. It is not an empty hull; it is still packed with 1,400 tons of high explosives, making it one of the largest unexploded ticking time bombs on the planet.For over eight decades, the British government has faced a paralyzing dilemma. Attempting to move the degraded, unstable munitions could trigger an explosion large enough to generate a...