Imagine a nuclear weapon so dangerous that its bombs were almost an afterthought. During the height of the Cold War, the United States developed Project Pluto and its terrifying offspring: the Supersonic Low Altitude Missile, or SLAM. Powered by an unshielded nuclear reactor, the missile was designed to fly at Mach 3 just a few hundred feet above the ground, carrying multiple hydrogen bombs while blasting everything beneath it with deafening shockwaves and a trail of radioactive exhaust. Unlike conventional missiles, it required no fuel and could theoretically remain airborne for days, crossing continents before unleashing its payload. Engineers successfully built and tested the nuclear ramjet that made the concept possible, proving that one of the most extreme weapons ever conceived could actually work. Yet as the project moved closer to reality, military planners began to realize that

Source: America’s Forbidden Doomsday Machine