Experts are puzzled by President Donald Trump’s call last week for the United States to resume nuclear weapons testing.
Did he really mean detonating warheads or testing delivery systems? Does he understand how nuclear weapons work? How will America’s nuclear adversaries react?
Some experts also warn that testing nuclear warheads that produce actual nuclear explosions could harm humans and have lasting effects for generations.
Few people know that nuclear tests can cause more harm than the residents of the Marshall Islands, a nation of 1,200 islands and atolls in the Pacific Ocean. The Marshall Islands was a United Nations trust territory administered by the United States from 1947 to 1986.
After World War II, the United States developed nuclear weapons and detonated 67 nuclear bombs between 1946 and 1958.
According to a 2025 report by the Institute for Energy and Environment Research (IEER), these explosions had the explosive power of one Hiroshima-sized atomic bomb every day for 20 years.
A U.S. government report cited by the Nuclear Heritage Foundation said the effects of radiation were devastating and that the tests were responsible for 55 percent of cancer cases in parts of the island’s northern atoll.
And its influence extends far beyond the islands. Nuclear fallout from these tests is dispersed by winds in the atmosphere, leading to about 100,000 excess cancer deaths worldwide, according to an IEER study. Fallout hotspots have been detected as far away as Sri Lanka and Mexico.
According to a 2024 paper published in the Journal of the American Society of Clinical Oncology, the associated disease is derived from isotopes in nuclear fallout that can penetrate the human body and cause mutations in DNA.
The isotope can remain in the environment for years after the test, potentially harming people exposed to lung, leukemia, lymphoma, thyroid, breast and other cancers, the paper said.
And past U.S. nuclear tests were not limited to Pacific islands. The Nevada Test Site in the Mojave Desert hosted 100 atmospheric experiments and 828 underground experiments from 1951 to 1962, the last in 1992.
Although underground tests are considered safer, 32 of the tests conducted in Nevada resulted in fallout leaking into the atmosphere, according to a 1993 United Nations report.
“We know that nuclear testing has had devastating effects on communities and ecosystems across the United States, many of whom are still seeking reparations for the harm caused by U.S. nuclear testing during the Cold War,” said Matt Korda, deputy director of the Nuclear Information Project at the Federation of American Scientists.
“Resuming testing will almost certainly cause new harm to these groups,” Korda told CNN.
The scars of nuclear testing are still fresh in the Marshall Islands.
“This is not fiction or the distant past. This is a chapter in history that is still alive through the environment, the health of our communities, and the data we collect today,” Greenpeace activist Sean Barney wrote after visiting the island earlier this year.
Environmental groups conducted a voyage to the Marshall Islands in March and April of this year to document conditions there and collect scientific samples for future reports on the islands.
Small Runit Island, part of Eniwetak Atoll, is home to the Dome, a 377-foot (115-meter) diameter structure made of concrete about half a meter thick. According to Greenpeace, beneath it lies 85,000 cubic meters of radioactive waste collected during efforts to clean up the islands in the 1970s.
Unlike the new nuclear waste repository, the crater under the dome has no lining, so “these materials are not only confined within the crater, but also present throughout the island’s soil, rendering Runit Island permanently uninhabitable,” Burney wrote after the organization’s visit.
The island “may be one of the most radioactive places in the world,” he says.
And with climate change, rising sea levels threaten the aging dome’s structural integrity. No one knows how far the impact of that waste will spread.
“That dome connects the nuclear age and the climate change era,” activist Alson Keren said in a 2018 report by Australian NGO Safeground.
Mr Birney said radiation in the environment had changed the lives of the 300 current residents across Eniwetak Atoll. It was taken into the roots of coconut palms and contaminated the fruit, making it impossible to distribute it to the market.
“The legacy of radioactivity has robbed them of income and opportunity,” Barney said of the islanders.
According to the IEER report, agriculture is not the only industry affected. As their way of life deteriorates, traditional skills, such as open sea navigation necessary for commerce and reproduction, are being lost.
The IEER report cites a 2016 New York Time report on the island’s sailors, which says reading the waves was “essential as the only way to gather food, trade goods, wage war, and find unrelated sexual partners.”
UN Deputy High Commissioner Nada Al Nassif told the UN Human Rights Council in 2024 that the legacy of testing is separating indigenous Marshallese people from their culture.
“The human rights impacts of nuclear legacies are not limited to what is known and easily quantifiable; they are also rooted in unmeasurable pain and facts that remain unknown,” she said.
Bravo Castle and Bikini Atoll
About 300 miles east of Eniwetak is Bikini Atoll, where the United States conducted the largest nuclear weapons test in history. This bomb, known as Castle Bravo, was a thousand times more powerful than the Hiroshima atomic bomb.
In 1946, Bikini Atoll had 167 inhabitants. Before the Castle Bravo experiment, U.S. naval officers persuaded them to leave their homes “for the good of humanity.”
“He explained that they were a chosen people who could prevent future wars by perfecting their nuclear arsenal,” and would one day be allowed to return home, the Atomic Heritage Foundation’s history says.
Bikini is currently unmanned, with a few caretakers. Radiation levels are still too high for full-time habitation, a decision made after Bikini residents were allowed to return in 1969 and began suffering from radiation-related illnesses. The island was closed again in 1978.
“Most of the new generation of Bikinians have never seen their home island,” Greenpeace’s Bernie wrote.
The final stop on Greenpeace’s island tour this year was Rongelap Atoll, about 125 miles (200 kilometers) northwest and covered in the ash of the Castle Bravo test in Bikini.
In a 2024 report, the International Campaign to Abolish Nuclear Weapons (ICAN) described the impact of the ash, known as “bikini snow,” on the population.
“They suffered burns to their skin and eyes and immediately developed symptoms of acute radiation sickness,” the report said.
And its influence was long-lasting.
“For decades after the experiment, women in the Marshall Islands gave birth to severely deformed babies at an unusually high rate. Those born alive rarely survived for more than a few days. Some had translucent skin and no discernible bones. They called them ‘baby jellyfish,’ because they were almost unrecognizable to humans,” the ICAN report said.
Seeking relief, residents of Rongelap were evacuated from the island in 1985 with the help of Greenpeace and resettled on two islands in Kwajalein Atoll. Both islands are just a few miles from the Ronald Reagan Ballistic Missile Defense Test Range, which is operated by the U.S. military. The test site reportedly supports nuclear-capable missile tests and interceptions.
Although no nuclear tests have been conducted in the Marshall Islands since 1958 (the current U.S. nuclear test site is located underground in Nevada), the last nuclear test in the Pacific was conducted by France in 1996, one of 193 conducted by Paris on the South Pacific atoll over a 30-year period.
According to a 2021 report by French investigative reporting site Disclose, Princeton University, and Norwegian NGO Interprint, around 110,000 people suffered radiation sickness during tests in France.
“Leukemia, lymphoma, thyroid cancer, lung cancer, breast cancer, stomach cancer… In Polynesia, the experience of French nuclear testing is etched in the flesh and blood of the population,” the report said.
The last French test, on January 27, 1996, resulted in massive international protests and a boycott of French products.
The next day, then-French President Jacques Chirac announced that his country would no longer test nuclear weapons.
In late July 1996, China conducted a nuclear test at the remote Lop Nor base in northwestern Xinjiang. This was the last test by a major nuclear power.
In September 1996, the Comprehensive Nuclear-Test Ban Treaty (CTBT) began to be signed. The clause obliges signatories “not to conduct any nuclear weapon test explosions or other nuclear explosions.”
The United States, Russia, and China quickly signed, but have not ratified. Although it is not legally enforceable as it still needs to be ratified by nine countries, three countries have complied with it.
The only nuclear tests known to have taken place in the world since 1996 have been by India (two in 1998), Pakistan (two in 1998), and North Korea (six from 2006 to 2017). None of these countries signed the treaty.
President Trump’s social media posts on Thursday calling for the United States to resume nuclear testing have raised fears that a new nuclear arms race could begin, with even more devastating consequences for people around the planet.
“This is a dangerous moment,” anti-nuclear group Plowshares said in a statement, calling the president’s announcement “reckless, unnecessary and dangerous.”
The likelihood of another nuclear explosion within the Marshall Islands’ borders is highly unlikely, as the United States plans to conduct weapons tests beneath the Nevada desert.
However, the effects of nuclear weapons will remain on these islands forever.
Plutonium-239, one of the remains of U.S. nuclear tests, has a radioactive half-life of 24,110 years.
