Issues affecting atomic veterans date to the dawn of the nuclear age, with the bombs dropped on Japan in 1945. The United States then spent years trying out new designs for its growing nuclear arsenal. More than 200 tests were conducted in the atmosphere from 1946 to 1962, in the Marshall Islands and at sites in the Nevada desert. Many thousands of soldiers and sailors — numbers are elusive, but some estimates go as high as 400,000 — observed the explosions on the sea or in trenches a few miles from ground zero.

They were men like Frank Farmer, who witnessed 18 atomic detonations in 1958 while stationed on a ship in the Pacific. “You feel the heat blast from it,” Mr. Farmer, now 80, said in the video. “It’s so bright you actually see your bones in your hands.”

He and his shipmates were issued no protective gear. “I was wearing a T-shirt and dungaree pants, that’s all,” he said.

A 1963 treaty banned atmospheric tests. Experimentation went underground or, less commonly, underwater, continuing into the early 1990s. But long before then, atomic veterans sensed that things were not going well for them. Despite government assurances that their exposure to radiation had been insufficient to inflict physical harm, veterans could see they were getting sick in disproportionate numbers. Some began to speak out, ignoring oaths they had signed never to discuss their experiences.

“More and more I heard about guys that had prostate cancer and lung cancer and all kinds of cancers,” said Mr. Farmer, who suffered hearing loss and a body rash that did not go away.

Lincoln Grahlfs, who steered a Navy tugboat near atomic test sites in the Marshalls in July 1946, has chronically labored with boils. Now 93, he is convinced that his offspring, too, paid a price. A daughter died of a brain tumor at 46. Her daughter was born with a deformed foot.

“I wish somebody had warned me that if I had children, they might be born with some defects,” Mr. Grahlfs said. “But nobody did.”

In some instances, experiments went well beyond having American service members as bomb-test bystanders. In the early postwar years, for example, 18 patients in civilian hospitals were injected with radioactive plutonium without their knowledge. More than two dozen other patients were radiated over their entire bodies — not to treat medical problems but, instead, to see what the effects would be.

Decades passed before corrective measures were taken. While it can often be difficult to prove a cause-and-effect relationship between military duty and a malady, Congress in 1988 established a system of compensation. It specified 13 kinds of cancer — a list later expanded to 21 — that were presumed to have been the result of exposure to radiation.

Early in his presidency, Bill Clinton created an Advisory Committee on Human Radiation Experiments to review the consequences of nuclear testing. On the panel’s recommendation, Mr. Clinton apologized for past official actions. “When the government does wrong, we have a moral responsibility to admit it,” he said on Oct. 3, 1995.

The timing proved unfortunate. That same day, a California jury acquitted O. J. Simpson in his murder trial, and the presidential apology got lost in the news swirl. Mr. Farmer and Mr. Grahlfs never heard it.

Compensating aggrieved veterans did not always go smoothly. In many cases, it was not clear from available records if a man had, in fact, been stationed near a bomb test. And there was an ineluctable reality: By the time the government got around to cutting checks, many of the men were dead.

Issues raised by their difficulties resound in modern wars. As with the atomic veterans, officialdom’s default position has generally been to wave off any suggestion of a link between a soldier’s illness and a command-level decision. That was the case with Agent Orange, the most notorious defoliant used by the American military in Vietnam. Years passed before the government accepted a “presumptive” connection between herbicides and cancers afflicting Vietnam veterans.

In conflicts of more recent vintage, soldiers who served in Afghanistan and Iraq and in the 1991 Persian Gulf war complain of breathing problems, neurological damage, gastrointestinal disorders and other illnesses. Many suspect that blame lies with practices off the battlefield.

In Afghanistan and Iraq, all manner of waste — batteries, plastics, medicines, dead animals — was soaked in jet fuel and set ablaze in open pits. Men and women standing nearby breathed in poisons. Other soldiers handled armaments made of depleted uranium, a heavy metal with toxic properties. As for a multi-symptom malady known as gulf war illness, studies done for the Department of Veterans Affairs estimate that it has afflicted more than one-third of the nearly 700,000 service members assigned to the Middle East in 1990 and 1991.

Again, the official stance has been that no conclusive evidence ties medical problems to wartime practices. Compensation for Iraq and Afghanistan veterans is not on the table. Similarly, there has been scant congressional movement on a bill to compensate soldiers who were dispatched in the 1970s to the Marshall Islands (where cancer rates were predictably high) to haul away radiation-tainted debris.

Within the diminishing cadre of atomic veterans, some feel as if they embody a biblical sentiment expressed in the Book of Micah and repeated in Matthew 10:36: “And a man’s foes shall be they of his own household.”

Mr. Farmer recalled how he and his mates, for weeks, drank and bathed in fallout-contaminated water. “For people that’s smart enough to become admirals and presidents,” he said, “you’d think they’d have enough sense not to put you into something like that.”

CLYDE HABERMAN, a regular contributor to Retro Report, has been a reporter, columnist and editorial writer for The New York Times, where he spent nearly 13 years based in Tokyo, Rome and Jerusalem. Subscribe to our newsletter here and follow us on Twitter @RetroReport.

This article first appeared in The New York Times.