As the world marks 81 years since the atomic bombings of Japan, only a handful of Americans remain who witnessed the aftermath.

They’re called “atomic veterans”—servicemen who arrived in Hiroshima and Nagasaki in the weeks after the bombs were dropped. Of the millions of Americans who served in World War II, only a small fraction—roughly 67,000—were assigned to those Japanese cities as part of the Allied occupation. Many were teenagers, sent into the two cities to keep order, in some cases helping to treat the tens of thousands of Japanese civilians who had survived the blasts but were dying of injuries no one yet fully understood.

When we set out to make the 2025 PBS documentary, Atomic Echoes: Untold Stories of World War II, we knew it was a race against time. Fewer than 10 of these American atomic veterans were still alive, and one of the three we included in the film—Michas Ohnstad of North Branch, Minnesota—passed away earlier this year. The film explores the trauma and legacy of nuclear war through interviews with both American veterans and Japanese survivors. Their stories tell the unbearable truth of nuclear holocaust that new generations should know.

Witnessing the unthinkable. Archie Moczygemba of Taylor, Texas, turned 102 on July 4. A Marine assigned to the occupation of Nagasaki, he arrived in September 1945. Larry Pressley of Columbia, South Carolina, will celebrate his 100th birthday this September. He was also assigned to Nagasaki, although the two never met.

We reinterviewed them in July to ask what messages they most want future generations to know.

Moczygemba, the Texan, recalled a detail he didn’t mention in the film: “We walked through a hospital shortly after we arrived. All the metal beds were just crumpled against one wall. The sheer power of the bomb—it was unthinkable.”

The veteran struggles with his short-term memory now, but the images of Nagasaki have stayed with him for 81 years. Moczygemba remembers vividly the patterns of women’s kimonos, burned directly onto their skin by the heat of the blast—a detail so specific and so haunting that eight decades later, he still lives with it. “The blisters on people’s skin,” he says, “It’s something a lot of people don’t talk about, what the exposure did to those who survived it.”

The nuclear weapons that exist today are in an entirely different class than those used against Hiroshima and Nagasaki. Some modern nuclear warheads deployed today are 50 to 100 times more powerful than the atomic bombs detonated in 1945.

Breaking the silence. For decades, much of what the atomic veterans saw was classified. Many were ordered never to discuss what they had witnessed—an oath some carried for nearly half a century before the government eased those restrictions in 1996. Even then, connecting a specific illness decades later to months spent in an irradiated city proved to be its own battle—and some atomic veterans fought against the Department of Veterans Affairs for years, with mixed results.

The two atomic veterans both count themselves lucky. Many of the men they served alongside did not live long enough to tell their stories.

Pressley of South Carolina remembers how the Marines brought only limited water to Nagasaki for drinking and cooking. They showered in contaminated water, and many of them also drank it—something he believes contributed to servicemembers’ radiation-related cancers later in life.

The former Marine is aware of how different the use of nuclear weapons would be today. “It’s almost meaningless to even discuss it,” he says. “You can’t drop another atomic bomb—ever. There would be immediate retaliation.”

As one of the last American witnesses of nuclear holocaust, his warning carries a weight and perspective few others can claim.

Preserving atomic memories. The testimonies of the last atomic survivors come as the global nuclear landscape becomes increasingly unstable, with nuclear powers engaged in an escalating arms race. The risk of nuclear weapons being used is higher today than at any point since the end of the Cold War.

Statistics can sometimes numb people to the stakes rather than clarify them. What projects like Atomic Echoes aim to do is focus on the specificity—like the chrysanthemum-shaped kimono burns Moczygemba remembers seeing in Nagasaki, or the Geiger counters that both soldiers wore to measure radiation that never stopped squealing.

It’s a difficult subject to put on a screen even 80 years later.

Christopher Nolan, in his 2023 film Oppenheimer, chose not to show the horrors of the atomic bombings, and Hollywood’s Doomsday films have ranged in their effectiveness. But we continue to emphasize the stories of the humans behind—and below—these weapons.

And after all American and Japanese eyewitnesses are gone, the living bridge between today’s world and the only wartime use of nuclear weapons will disappear, forcing storytellers to find new ways to tell their stories.

There have been efforts to preserve the testimonies of hibakusha (Japanese survivors) as well as Manhattan Project scientists, including the use of technology like AI and virtual reality (VR) to show the memories of atomic warfare. And in Japan, one can now stand at several points in the city and, through a VR headset, see what it was like when the bomb dropped and the city burned to the ground.

We hope the voices of the last American atomic veterans—including the veterans of US atmospheric testing in the Marshall Islands—will similarly be preserved and amplified as their numbers get smaller.

Every American atomic veteran we spoke to for the film told us that they’d never been asked to publicly share their stories. Not once in 81 years. This is a collective failure. In truth, historians, journalists, and filmmakers alike should be asking these veterans about their lived experience. We can’t afford to let the human consequences of nuclear war become an abstraction.

“I was one of very few people to experience it,” Moczygemba says. “And I’ll never forget it.”