Special Atomic Demolition Munition
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The Special Atomic Demolition Munition (SADM) was a family of man-portable nuclear weapons fielded by the US military in the 1960s, but never used in combat. The US Army planned to use the weapons in Europe in the event of a Soviet invasion. US Army Green Light Teams or Engineer Atomic Demolition Munitions Specialists, would use the weapon to destroy, irradiate and deny key routes of communication through limited terrain such as the Fulda Gap. Troops were trained to parachute into Soviet-occupied western Europe with the SADM and destroy power plants, bridges, and dams.
It was also intended that the munition could be used against targets in coastal and near-coastal locations. One person carrying the weapon package would parachute from an aircraft and place the device in a harbor or other strategic location that was accessible from the sea. Another parachutist without a weapon package would follow the first to provide support as needed. The two-man team would place the weapon package in the target location, set the timer, and swim out into the ocean, where they would be retrieved by a submarine or a high-speed surface water craft.
Other lightweight nuclear devices
In the 1950s and 1960s, the United States developed several different types of lightweight nuclear devices. The smallest of these was the W54 warhead, which had a 10.75 inches (273 mm) diameter, was about 15.7 inches (400 mm) long, and weighed approximately 51 lb (23 kg). It was fired by a mechanical timer and had a TNT equivalent between 10 tons and 1 kiloton. The W54 nuclear device was also used in the Davy Crockett Weapon System and in the GAR-11/AIM-26A.
Atomic Demolitions Munitions School
The Atomic Demolitions Munitions School was located at the US Army Engineer Center on Ft. Belvoir, Virginia, until it was closed in 1985.
Suicide attack allegations
On December 27th, 2018, the Green Bay Press-Gazette interviewed veteran Mark Bentley, who had trained for the Special Atomic Demolition Munition program to manually place and detonate a modified version of the W54 nuclear bomb. The report stated that he and other soldiers training for the program knew this was a suicide mission because either it would be unrealistic to outrun the timer on the bomb, or that soldiers would be obligated to secure the site before the timer went off. However, in theory the timer could be set long enough to give the team a chance to escape. Specifically, he stated, "We all knew it was a one-way mission, a suicide mission."  "You set your timer, and it would click when it went off, or it went ding or I forget what, but you knew you were toast," he said. "Ding! Your toast is ready, and it's you." He also commented, "The Army is not going to set a bomb like that and run away and leave it, because they don't know if someone else would get ahold of it," he said. "They have to leave troops there to make sure it's not stolen or compromised, and that would just be collateral damage. You didn't go out with the thought that it was anything other than a one-way mission. If you're Bruce Willis, you get away, but I ain't Bruce Willis."
Others, who are familiar with the weapon yield and design, note that the blast is small enough that the placement team can survive the explosion given the amount of time provided by the detonating timer. However, recovering that placement team would be nearly impossible due to the hue and cry raised after such a nuclear attack. It is far easier to infiltrate to the target while the population is unaware, but a roused and angry population would make escape and evasion a nearly futile effort. 
- Paul Srubas, Green Bay (Wis.) Press-Gazette via the AP (January 7, 2019). "His job was to place atomic bombs. Place them, not drop them. Set the timer. Run like hell". Green Bay Press-Gazette.
- SWOP W54-25
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