The stated reason for the development of the landmines and other ADMs was to give a small group of soldiers, or even an individual, the ability to destroy enemy facilities or to create no-go areas to change the layout of the battlefield. The landmines would likely have been detonated remotely or by timer, rather than by pressure as with some more common conventional landmines.

“[ADMs] were intended mostly for what you might call nuclear landscaping — to create irradiated, impassible craters or to collapse mountainsides into narrow passes in order to obstruct likely invasion routes and bottleneck enemy forces,” says a 2014 Foreign Policy report on ADMs and the Army soldiers who trained with them. “One engineer recalls setting up an ADM in the middle of a forest: ‘The idea was to blow these trees across a valley to create a radioactive physical obstacle for vehicles and troops to get by,’ he said. The Army’s countermobility field manual taught soldiers to use ADMs for ‘stream cratering,’ in which atomic explosions near small waterways would ‘form a temporary dam, create a lake, cause overbank flooding, and produce an effective water obstacle’ for enemy forces.”

In September 1967, NATO’s Nuclear Planning Council held discussions about the use of ADMs and a meeting summary said that “while agreeing that conditions may vary in different areas, [the council members] recognized that in certain circumstances the use of atomic demolition munitions might have significant military advantages by creating obstacles as part of a comprehensive defence system.” The group agreed to study the issue further.

But an equally important, though unstated reason for the development of ADMs, according to Schwartz, was that the U.S. Army wanted desperately to get into the nuclear game, which at the end of the Second World War was dominated by the Air Force.

“The larger over-arching picture: This was developed in a time when the Army was grasping for relevance in the nuclear age,” he said. “There were two arms races during the Cold War. There was the one we all know about, which was the United States vs. the Soviet Union. But then the lesser known one, what drove a lot of procurement decisions, and that was the inter-service rivalry between the Air Force, the Navy and the Army. And the Army in particular was scrambling…

“All this money, all this prestige was attached to this new weaponry and the Army needed a mission. So what did they do? They created requirements for a nuclear weapon,” said Schwartz, who is also an adjunct professor at Middlebury Institute of International Studies at Monterey. Overall, the Army eventually acquired 26 different kinds of nuclear weapons.

But Schwartz said that after the weapons were in the field, the Army realized the ADMs were more trouble than they were worth. They required specialists to do upkeep, they didn’t fit well in the order of battle, they were potentially a threat to America’s own troops and there were a host security concerns. A declassified 1985 CIA document on Chinese nuclear capabilities said that the Chinese military at the time was not believed to have ADMs or to have much incentive to build them since they were “difficult to emplace quickly or in combat and may not be in the right place when they are needed.”

Perhaps the biggest worry, Schwartz said, was that the use of any nukes by the U.S. would provoke the “other side” into responding with their own, larger nuclear weapons, ending in catastrophe for both. Cold War-era CIA documents indicate that Soviets did not have ADMs either back then, but had plenty of other strategic and tactical nuclear weapons at the ready. The Soviet defense doctrine called for a “massive” response to any use of nuclear weapon — including an ADM, U.S. analysts believed.

From there, as a 1970 CIA memo put it dryly, “there is… no assurance for either side that waging war in Europe with nuclear weapons would result in a favorable outcome.”

“This whole concept was ridiculous,” Schwartz said. “And no one really thought through why they were doing this other than the fact that it was good for the Army.”

For some or all these reasons, the four types of nuclear weapons that the Bulletin of the Atomic Scientists said were designed to be used as landmines were only operational for a few years, from the late-1950s to the mid-1960s. But at least two of their ADM cousins stayed in service for decades, and the Army kept up the training of atomic demolition specialists, before the program was shut down as part of a larger nuclear drawdown in the 1980s.

This summer, some former Army atomic demolition soldiers reportedly got together for a rare reunion at Fort Leonard Wood in Missouri. Despite the now-questionable use of the nuclear landmines and other ADMs or bureaucratic decisions made far above the ex-soldiers’ heads, one of the former engineers said the men he trained with “feel that we did our service proudly and effectively.”

“We are a small, close-knit group of people who were dedicated to one purpose, and one purpose only, and that was to defend the United States in case of conflict,” Larry Wetta, who trained to be an atomic demolition specialist in the 1960s, is quoted as saying.

It’s a strange chapter in Cold War history, and there’s no indication the U.S. is going to head back down the road of nuclear landmines. While Trump previously said he wanted to “expand” America’s nuclear arsenal, potentially restarting a Cold War-style arms race, he assured reporters more recently he only wants America’s existing nuclear forces in “perfect condition.”