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Special Forces Parachuted With Nukes Strapped To Them During The Cold War Special Forces “Green Light” teams trained to deploy small nuclear bombs called Special Atomic Demolition Munitions during the Cold War.

BY
OLIVER PARKEN
|
PUBLISHED JUN 9, 2023 5:32 PM EDT
Green Beret conducts high-altitude freefall jump with an SADM
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For U.S. special operations personnel, conducting high-altitude
parachute jumps are pretty much par for the course. Yet doing so with a
nuclear bomb strapped between your legs is on an entirely different level.

That’s exactly what can be seen in the top shot above. Here, a U.S. Army Special Forces paratrooper is pictured free-falling during a training
exercise with a Special Atomic Demolition Munition, or SADM, harnessed
to them. A form of atomic demolition munition (ADM), SADMs were
man-portable nuclear weapons, also known as "backpack nukes." These
munitions were fitted into specially designed hard/cloth carrying cases
for their transportation on the backs (or between the legs) of special operators. SADMs weighed in the region of 150 pounds, with their
warheads – the W-54/B-54 – contributing around 50-55 pounds. SADMs were extremely small, just 24 inches long by 16 inches wide.


But why did special operations personnel train with these munitions? In
order to unpack this question, we need to look back to the 1950s and
1960s when the U.S. began to diversify its nuclear weapons capabilities.

The atomic blasts at Hiroshima and Nagasaki in August 1945 imparted a
level of devastation never before seen in the history of human conflict.
Just a few years later, the Soviet Union detonated its first atomic bomb
in August 1949, codenamed “Joe-1” by the U.S. While the U.S. military conducted further tests of such weapons into the early part of the Cold
War, a broader view emerged that smaller nuclear weapons for limited
tactical purposes would likely prove critical for operations on the
ground in future conflicts.

Mushroom cloud pictured following the Hiroshima bombing, August 6, 1945.&nbsp;<em>Bettmann via Getty Images</em>
Mushroom cloud pictured following the Hiroshima bombing, August 6, 1945. Bettmann via Getty Images
Indeed, the idea of using tactical nuclear weapons in a possible
conflict involving the Soviet Union became an important component of
President Dwight D. Eisenhower’s ‘New Look’ policy during the early to mid 1950s and into the early 1960s. As such, scientists and technicians
at the Los Alamos and Sandia nuclear weapons laboratories began
miniaturizing the size of the warheads used in nuclear weapons.

At the same time, the U.S. Army was making moves to acquire different
sorts of battlefield nuclear weapons, including short-range ballistic
missiles and the infamous M28/M29 Davy Crockett recoilless gun which
fired nuclear warheads with a yield of roughly 10-20 tons of TNT. Part
of the push towards fielding a broader range of nuclear weapons by the
Army also included the development of atomic demolition munitions (ADMs).

Davy Crockett recoilless gun. <em>U.S. Army</em>
Davy Crockett recoilless gun. U.S. Army
ADMs were designed to be used on or below the ground’s surface (or even underwater) against specific targets to block and deny enemy forces. The initial objective of ADMs was to manage nuclear landscaping – creating
giant craters or destroying mountainsides that could obstruct enemy
forces. It was envisaged that small teams of engineers or special
operations forces would carry and operate ADMs.

The munitions first entered the U.S. Army’s nuclear arsenal in 1954,
with one of the first ADM tests taking place during Operation Teapot
(1955), part of a series of nuclear tests conducted at the Nevada Test
Site. During said test, an 8,000 pound ADM bomb with a yield of 1.2
kilotons was detonated, creating a crater 300 feet wide and 128 feet deep.

Into the 1960s, a whole family of ADMs was developed. This included the Tactical Atomic Demolition Munition (TADM), sporting a W-30 warhead.
TADMs weighed around 840 pounds as a complete system, and around 300
were produced between 1961-1966. Medium Atomic Demolition Munitions
(MADM) were also developed. Sporting the W-45 warhead, each weighed
around 400 pounds. 350 MADMs were produced between 1962-1966. The
warhead on both TADM and MADM munitions could be customized for various
yields.

Internal view of a Medium Atomic Demolition Munition (nuclear landmine). <em>DoD</em>
Internal view of a Medium Atomic Demolition Munition (nuclear landmine). DoD Desiring a much lighter, man-portable ADM, the Army ended up producing
around 300 SADMs between 1964-1966. Production on an interim W-54 Mod 0
weapon started in April 1963, while the W-54 Mod 1 SADM was placed into production in August 1964. The Mod 1 SADM constituted the warhead, a fuzing/firing system, a mechanical timer, a ferroelectric firing set and
its sealed housing. Later, the W-54 Mod 2 SADM was put into production
in June 1965. At least two different SADM designs, the XM129 and XM159,
were created.


Carrying case for the Special Atomic Demolition Munition (SADM), a
tactical nuclear weapon. <em>Glen George McDuff via Wikimedia Commons</em> Carrying case for the Special Atomic Demolition Munition (SADM), a
tactical nuclear weapon. Glen George McDuff via Wikimedia Commons
At the heart of the SADM system was the W-54 tactical nuclear warhead.
The W-54 was developed in the late 1950s – initially by Lawrence
Livermore National Laboratory until early 1959 (designated the XXW-51),
and, thereafter, by the Los Alamos National Laboratory (then
re-designated the XW-54). The W-54 warhead measured just 16 inches in
length and 10.75 inches in diameter. The yield of W-54 warheads was
variable, from ten tons of explosive TNT to 1,000 tons of explosive TNT.

U.S. officials examine a M-388 Davy Crockett nuclear weapon. The W54
nuclear warhead was used in the man-portable&nbsp;M-388 Davy Crockett&nbsp;projectile. The unusually small size of the warhead is
apparent. <em>DoD</em>
U.S. officials examine a M-388 Davy Crockett nuclear weapon. The W54
nuclear warhead was used in the man-portable M-388 Davy Crockett
projectile. The unusually small size of the warhead is apparent. DoD
Compared to heavier ADMs, the Army envisaged that light weight SADMs
could more easily be used tactically for operations behind enemy lines
in Eastern Europe. In this sense, the munitions would be used to
frustrate enemy forces by blowing up fortified structures, tunnels,
mountain passes, and viaducts. Alongside their deployment via land or
sea, SADMs were also designed to be sent behind enemy lines from the
air. Two-man parachute teams – one individual carrying the disassembled weapon in a bag made of canvas – would descend to target points before setting up the device’s explosive timer. Owing to the U.S.'s nuclear
doctrine dictating that no single person ever have the means to employ a nuclear weapon on their own, teams of at least two would accompany the
bomb (with just one individual carrying it). The detonation code would
be split between the two special operators, with both halves needed to
start the weapon's countdown.

The idea of using Special Forces teams, known as “Green Light” units, to transport ADMs behind enemy lines had roots stretching back to 1956.
Indeed, using special operations units to harass and frustrate the enemy
using ADMs chimes with the historical origins of the Army's Special
Forces in the early 1950s. It was envisaged that these elite units would
'stay behind' in rear areas to target enemy forces and even mobilize
local resistance against them. However, early ADMs – such as the ADM-4 – were too large and heavy to be carried by one or two men. The production
of SADMs moved the concept along quickly.

To be selected for the Green Lights was a rare and highly secret thing.
As Annie Jacobsen notes in her book, Surprise, Kill, Vanish: The Secret
History of CIA Paramilitary Armies, Operators, and Assassins, Green
Lights personnel were pulled from Army Special Forces, Navy SEAL units,
and the Marines. Units worked under pseudonyms, and wore fatigues with
no markings or insignia. Initial training involved learning infiltration techniques including parachute launches and wet-deck submarine launches. Overall, the instruction of Green Light units took place over the course
of a week, consisting of eight to 12 hours each day.

Parachute missions involving SADMs were performed over the sea, as well
as over land during the 1960s and 1970s, in order to train for their
potential detonation overseas. In 1972, Green Light units parachuted
near the White Mountain National Forest in New Hampshire. As Foreign
Policy notes, the nuclear weapon used was a training dummy. Navy SEALs
also performed underwater training with the munitions. Moreover, drills
with the SADMs also occurred outside the U.S., with Special Forces teams
even skiing with them in the Bavarian Alps during, for example.


“Timing was everything” when it came to parachuting from planes with nuclear weapons, Billy Waugh recalls of his time with the Green Lights
in Surprise, Kill, Vanish. “You had to jump quickly – you couldn’t
afford to be spread out when you landed on the ground.” Indeed, the jumper’s rigging was designed in such a way that the nuclear component
would fall to the end of a 17-foot-long lowering line once outside of
the aircraft.

Parachute training with an SADM. <em>Sandia National Laboratories
archive photo</em>
Parachute training with an SADM. Sandia National Laboratories archive photo Once SADMs were fixed in place, and their detonation charges triggered,
Green Light personnel needed to retreat to a ‘safe’ location to avoid
being caught in the explosion. This would have been a difficult task
given that the timers could not be relied on for complete accuracy. As
Army field manuals from the time indicated, it was “not possible to
state that [SADM timers] will fire at a specific time.”

Furthermore, there was also the fact that Green Light teams would also
have had to make their way out of enemy territory once the munition was detonated. According to Bill Flavin, who commanded a Special Forces SADM
team during the Cold War, “there were real issues with the operational
wisdom of the program, and those who were to conduct the mission were
sure that whomever thought this up was using bad hemp.” Indeed, many
special operators accordingly described the work of Green Light teams as suicide missions.

As SADMs were never used on foreign soil during the Cold War, those
realities were, thankfully, never realized. That the U.S. military was
training Special Forces personnel to personally transport nuclear
weapons behind enemy lines gained wider traction publicly in 1984.
Ex-Army intelligence officer William Arkin and colleagues presented
sketches and descriptions of the SADM to the Natural Resources Defense
Council, with the revelations reverberating within Congress and among
the public. From there, the weapon was slowly phased out, and was
officially retired in 1989.

So there you have it, the crazy history behind the U.S. military’s
SADMs. The next time you think that your job is stressful, just remember
you don’t have a nuclear bomb literally strapped to you as you jump out
of a perfectly good airplane.

Contact the author: oliver@thewarzone.com

Patrick Chase
9 June, 2023

Probably worth noting that the warhead in question had a yield of only
20t in the Davy Crockett (~2x MOAB's yeild) and 250t in the AIM-26
"Nuclear Falcon", though it is believed that the primary could yield up
to 1 kt. If the SADM was at the lower end of this range this means that
getting out of the lethal radius of the blast actually wouldn't have
been at all difficult, provided the team stayed upwind and kept some
terrain between themselves and the fireball to block prompt neutron and
gamma radiation. Getting out of enemy territory would be the hard part.

The other thing I've always found interesting about W54 is the way it demonstrates the tension between minimum weight and minimum
size/diameter in a nuclear weapon. The W54 uses spherical implosion and
is 10.5" in diameter (i.e. pretty bulky) but only weighs 50 lb. In
contrast, the contemporary W48 used linear implosion to get the diameter
down to 6", but weighed 120 lb. The later W82 got that down to 95 lb for
a 6" linear-implosion weapon. Basically the difference is that spherical implosion allows you to assemble a supercritical mass from a smaller
amount of fissile material, but is inherently bulky.

This is why "suitcase nukes" as featured in many spy thrillers are best
viewed as an urban legend. You can make them light, or you can make them suitcase-sized, but not both.


SpaceWinnebago
9 June, 2023

Fascinating! TIL… The only association I have with suitcase nukes is an equally sketchy factoid (that maybe I half remember from a nonsense Tom
Clancy novel or James Bond?) suggesting that should WWIII break out, one
of the missions of Soviet Spetsnaz would be to plant/detonate suitcase
nukes in st...

Patrick Chase
9 June, 2023

A Russian GRU defector claimed in the 90s that such a plan had existed,
and that the weapons weighed 50-60 lbs each. That's about the same as
the SADM, so it's credible if the "suitcase" was 11" thick. Perhaps the Russians improved on W54 a bit, though not much has changed since it was designed. Ba...

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Spursfan10
2 days ago

Are most of our warheads linear-implosion designs?


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Patrick Chase
2 days ago
Replying to Spursfan10

No, There is absolutely no reason to do linear-implosion unless you're
trying for really small diameters (as in the aforementioned W48 and W82,
which were both 155 mm artillery shells). We don't operate nuclear
artillery any more, so AFAIK there are no more linear-implosion fission devices.

It's probably worth noting that there are intermediate options that are
still in use. The 550 kt W88 is known to use a prolate (egg-shaped)
primary, which allowed it to be packed into an RV of similar size to the
120 kt W76. Specifically the prolate primary could be shoehorned into
the top of the RV, allowing for a larger secondary in the wider bottom
part of the conical RV, whereas the W76 has a much smaller secondary the
top.

It's also worth noting that clever profiling of explosives and air gaps
allows spherical implosion with an aspherical explosive "shell" (though
still a spherical pit). My understanding is that this is near-ubiquitous
in modern weapons because it allows spherical implosion with a small
number of ignition points. IIUC the thing that makes the W88 unique is
that the pit itself (and the resulting compression) is aspherical.


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LaunchTomorrow
2 days ago
Replying to Spursfan10

Not these days, most of them are spherical implosion and usually two
stage. From what I understand, it's hard to do linear implosion
thermonuclear weapons.


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Patrick Chase
2 days ago
Replying to LaunchTomorrow

Hmm. Linear implosion weapons definitely achieve lower temperatures
(which is why they're so inefficient), and it would make sense that that
would impact the production and energy distribution of the thermal
X-rays needed for secondary compression.

I hadn't heard that said explicitly before now, but...

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George Spencer
13 hours ago

the W48 package was a bit smaller than 6 inches. The proof is that it
was wrapped in a 155mm artillery shell casing. so the actual nuke was
under 6 inches

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