Advocates say, however, that as many as 400,000 more U.S. veterans should be included, as they were exposed during operations and radiation cleanup efforts over the past 75 years.

Keith Kiefer, president of the National Association of Atomic Veterans, said veterans who cleaned up contaminated areas such as Enewetak Atoll in the Marshall Islands in the late 1970s; Palomares, Spain, in 1966; or those who were living in Japan or involved in the response following the earthquake, tsunami and subsequent partial meltdown at the Fukushima Daini Nuclear Power Plant in 2011, should be included.

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"I'm putting together a list right now about individuals that should be classified or qualified as an atomic veteran; whether [DoD] accepts that or not remains to be seen," Kiefer said during an interview.

A Pentagon spokesperson said the department must go through several steps before it can begin sending medals to eligible veterans, to include establishing eligibility criteria, designing a medal, finding the funding for and procuring the medals, and establishing procedures to apply.

"We are working diligently to finalize the medal's design, to develop and coordinate eligibility criteria, and to submit the proposed eligibility criteria to the Committees on Armed Services of the Senate and House of Representatives for comment pursuant to [the law]," said Pentagon spokesperson Lisa Lawrence.

Lawrence did not provide a timeline for the agency's work, but said that "the Department is confident it will meet the statutory requirement for establishing eligibility requirements for the medal."

Since 2019, veterans who served between 1945 and 1992 and were part of development of the U.S. nuclear program have been eligible for a certificate recognizing their service in the atomic age.

But the National Association of Atomic Veterans has been fighting for broader recognition and legislation that would improve health care and disability benefits for service members and their survivors through the Department of Veterans Affairs and the Justice Department, which oversees the national Radiation Exposure Compensation Act Program.

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Kiefer said the medal, as well as another provision in the NDAA that permanently designates July 16 as National Atomic Veterans Day, are important to the veterans and their families.

"The recognition often means a lot more to the spouses and the children of the veterans than the atomic veterans themselves," Kiefer said. "This has been a much tougher battle than it should have been."

But, he added, disability benefits and compensation are needed as well. He pointed to the case of Army veteran Paul Laird, who participated in the cleanup at Enewetak and died in 2019 after a long battle with multiple types of cancer.

July 16, 1945, marks the day the U.S. detonated the world's first atomic weapon at the Trinity test site, now part of White Sands Missile Range, New Mexico. Three weeks later, the U.S. dropped a uranium-fueled device on the Japanese city of Hiroshima, and three days after that, a plutonium weapon similar to the Trinity bomb on Nagasaki.

The U.S. conducted more than 1,000 nuclear tests afterward, until Sept. 23, 1992, when the last detonation took place during an underground test at the Nevada National Security Site, roughly 65 miles northwest of Las Vegas.

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Several bills have been introduced in Congress this year that would expand benefits for veterans exposed to radiation, including one that would extend the Radiation Exposure Compensation Act Program by 19 years.

The program, which provides money to individuals who developed cancer or their survivors who were exposed to atmospheric nuclear testing or, in some cases, mined the uranium needed to make weapons, is set to expire in June.

Two proposed pieces of legislation also seek to designate more veterans as eligible for health care and disability compensation through the VA.

The $282 billion Honoring Our Promise to Address Comprehensive Toxics, or PACT, Act, introduced in the House and the $223 billion Comprehensive and Overdue Support for Troops, or COST, of War Act, in the Senate would designate veterans who cleaned up Enewetak Atoll, site of dozens of nuclear tests in the 1940s and 1950s, and the aftermath of the "Broken Arrow" incident near Palomares in which a B-52 Stratofortress bomber disintegrated, dropping three hydrogen bombs on land and one in the Mediterranean, as eligible.

Kiefer fears, however, that the Radiation Exposure Compensation Act Program will expire and the two veterans toxic exposure bills are too expensive to get passed.

"It seems very disingenuous. Overall, the veterans should be taken care of because it's through no fault of their own they are in this situation and they wound up getting sick," he said.

The VA lists 21 types of cancer as presumed to be related to exposure to ionizing radiation, but many veterans don't qualify for disability compensation or health benefits either because the Defense Department has minimized the level of radiation exposure or service records don't reflect they were present during a blast, according to Kiefer.

Fewer than 2,000 current veterans receive disability compensation for radiation exposure from the VA.