This was the most destructive nuclear weapon ever conceived

The Cold War saw both sides of the Iron Curtain come up with new ways to inflict a nuclear apocalypse on one another — always in the hope that these methods would serve more so as a deterrent than a call to war.

Among the myriad bombs and missiles designed in the United States to counter the surging Soviet missile program was the Supersonic Low Altitude Missile, arguably the most destructive missile system ever conceived in the history of modern warfare.

Designed by Vought in the late 1950s, SLAM was theorized as a viable alternative to nuclear-tipped missiles and bombers, which were slow enough (at the time) to be intercepted and shot down by Soviet air defense systems. Created as part of Project Pluto, which was established to develop new engines for cruise missiles, SLAM quickly became the most advanced weapons project the US military had ever undertaken.

A Project Pluto prototype nuclear ramjet engine in a test cradle (Photo Wikimedia Commons)

Pluto’s real mission was to create nuclear engines for missiles, giving them a nearly unlimited range and the ability to reach any target around the world after being deployed from American launch sites. When equipped with a Pluto-originated engine, a SLAM could literally fly 113,000 miles without stopping — that’s more than four times around the equator with enough gas in the tank left for more flying.

It would carry dozens of small hydrogen bombs in canisters inside its fuselage, and would also be given a terrain contour matching (TERCOM) radar, allowing it to fly close to the earth in order to avoid enemy radar detection.

SLAM would be launched using rocket boosters, pushing the sleek missile up to its cruising altitude so that it could activate its ramjet engine. Once the boosters fell away, the nuclear ramjet would power up, allowing it to loiter indefinitely at high speeds while waiting for the order to attack.

And when that order came, all hell would break loose.

A mockup of the SLAM missile (Photo Vought)

Once the attack order was transmitted to a SLAM, it would descend down to less than 300 ft over land, flying at supersonic speeds while wreaking havoc with its sonic shockwaves, destroying anything that wasn’t hardened or sheltered along the way.

Its nuclear engine would spew out deadly toxic waste, fatally irradiating anybody and anything near its flight path.

Along the way, SLAM could attack between 14 to 26 targets, releasing one thermonuclear warhead for each objective from compartments on top of the missile while it accelerated away to find its next target. And when SLAM exhausted its nuclear payload, it would become a weapon on its own, flying into the ground and catastrophically melting down its own reactor, further irradiating the area around it.

By the mid-1960s, the project was scrapped. The advent of improved intercontinental ballistic missiles, which could be launched from land bases or submarines, rendered developing the SLAM moot. Once launched, ICBMs were virtually unstoppable, while a SLAM could still hypothetically be shot down.

SLAM was canceled in favor of ICBMs like this Titan II (Photo Wikimedia Commons)

That, and the SLAM was considered just too destructive. In addition to effecting a nuclear annihilation upon all of Eastern Europe and a hefty chunk of communist-controlled Asia, the missile would also release toxic waste into the atmosphere, potentially contaminating the area above the United States and its allies.

The missile couldn’t even be tested, since it was simply too dangerous. What if the nuclear engine failed in-flight, or the guidance system washed out and it flew over allied territory? Thousands upon thousands would be given a lethal dose of radiation as a result.

Rising costs were the final nail in SLAM’s coffin, ending it and Project Pluto for good in the summer of 1964. Apparently, there really is a thing as too deadly when it comes to weapons of war!

For a narrated visualization of this missile’s concept, check out the below video, created by Convair during the competition bid to build what would eventually become SLAM: