In June, the United States joined Israel’s operation against Iran, targeting underground nuclear facilities, including the Fordow fuel enrichment plant using "bunker busters" like the GBU-57A/B massive ordnance penetrator that only US B-2 bombers (right) are certified to carry. (Illustration by François Diaz-Maurin; original artwork and photo salmanalfa, MikeMareen / depositphotos.com)

Forty years ago this year, the Hollywood film Back to the Future featured an eccentric scientist, “Doc” Brown (played by Christopher Lloyd), accidentally sending his teenage friend Marty McFly (Michael J. Fox) back to 1955 in a plutonium-powered time-traveling car. As he battles to return to 1985, Marty encounters his young father, who is bullied by his supervisor, Biff Tannen, and meets his young mother, on whom Biff has a crush. But Marty’s teenage mother falls in love with Marty, threatening his own existence. To go back to 1985, Marty has no other choice but to make his future parents fall in love, which he achieves, much to Biff’s dismay.

Four years later, the movie returned with a first sequel in which Marty travels to 2015, this time to prevent his son from tarnishing his family’s reputation. But while in the future, a revengeful older Biff steals the time-travelling car to go back to 1955 and rewrite history: There, Biff becomes a successful businessman, opens a casino, and uses his money to influence US politics.

In many ways, 2025 resembled Back to the Future, and not only because Donald Trump—whom the trilogy’s villain Biff is admittedly based on—returned to the White House in January. Less than one year into his second term, President Trump has exhibited Cold War-era thinking several times already.

One week after entering the presidency, Trump announced his plan for a new, comprehensive missile-defense system that his administration later called Golden Dome and claimed would be built in three years at a cost of no more than $175 billion. Many missile defense experts have pointed to the project’s technical and policy flaws and called it a fantasy that will add to a long-running US missile defense debacle. The fantasy started with President Ronald Reagan’s dream of building a missile shield—which he called the Strategic Defense Initiative and that detractors called “Star Wars”—after record Soviet nuclear deployments in—wait for it—1985. Experts warned that the Golden Dome proposal is self-defeating, as it will prompt US adversaries to build more maneuverable missiles and use more decoys, rendering any national defense ineffective.

A few days after announcing his missile defense effort, President Trump told reporters about his desire to engage with Russia and China on denuclearization efforts. “There’s no reason for us to be building brand new nuclear weapons. We already have so many,” he said. “You could destroy the world 50 times over, 100 times over. And here we are building new nuclear weapons, and they’re building nuclear weapons, and China’s building nuclear weapons.” But New START, the only agreement constraining the number of strategic offensive weapons that the United States and Russia can deploy, is set to expire in less than two months. And as of writing, Moscow maintains that it hasn’t received any formal response.

Around the time of Trump’s denuclearization comments, his administration’s Department of Government Efficiency started firing new federal hires, including hundreds at the National Nuclear Security Administration (NNSA), the Energy Department agency responsible for the safety and security of the US nuclear arsenal. (Most of the NNSA employees fired were eventually rehired after a bipartisan uproar in Congress.) The NNSA and its network of national laboratories provide essential technical support to the State Department for nuclear arms control verification. In July, the Trump administration dissolved the State Department’s Bureau of Arms Control, Verification, and Compliance, which was responsible for policy, negotiation, and overall compliance reporting of arms control treaties.

In May, President Trump signed four executive orders on nuclear power to accelerate nuclear power plant construction in the United States and support new, smaller, and less-regulated reactor designs. One of the orders plans a “substantial reorganization” of the US Nuclear Regulatory Commission, a plan three former chairs of the NRC say would threaten the independence of the agency, possibly undermining the safety requirements for nuclear regulation.

The same month, a brief skirmish started at the border between India and Pakistan, which seemed to quickly escalate, prompting President Trump to call for restraint from both sides. As a ceasefire agreement that Trump said he helped broker was being announced, reports suggested that, during the conflict, Pakistan’s Prime Minister had convened the National Command Authority, apparently in response to India’s targeting of Pakistani military bases. The National Command Authority is responsible for Pakistan’s nuclear policy and operational decision-making. (Pakistan’s defense minister later denied that the meeting ever happened.)

Then came the worst international security crisis of the year.

In June, two days after Trump said Iran rejected the US proposal for a nuclear deal that included a demand that it stop enriching uranium on Iranian soil, Israel attacked Iran, targeting military leaders, nuclear facilities, and nuclear scientists. About a week later, the United States bombed three Iranian nuclear sites at Fordow, Natanz, and Isfahan. While Trump touted the attack as “very successful,” the status of Iran’s nuclear program remained unclear after the attack, and later reports suggested that Iran’s stockpile of enriched uranium may not have been destroyed. Some experts warned before the attack that destroying Iran’s enrichment plants would not eliminate the Iranian nuclear threat and that a US action might spur Iran to covertly sprint toward a nuclear weapon as quickly as possible.

In July, in a surprising congressional twist, the House passed the Radiation Exposure Compensation Act (RECA) reauthorization and expansion bill. As a result, communities affected by the 1945 Trinity nuclear test and uranium mining in areas of Idaho, Montana, New Mexico, Colorado, the Navajo Nation and all of Nevada, Utah, and Arizona, as well as downwinders in Guam exposed to fallout from the Pacific nuclear tests during the Cold War started receiving compensation for their radiation exposure this year. (These groups were not initially covered by RECA.)

As if the legacy of US nuclear testing wasn’t painful enough, President Trump suggested in October that the United States should return to nuclear testing, confusing experts who could not tell whether the president was referring to testing a nuclear delivery system (such as a missile) or testing an actual nuclear explosive device. Many experts had already explained how resuming nuclear explosive testing would be impractical and against US security interests.

There have been many other nuclear developments in 2025 that also pointed in the direction of more risk and more instability. But one stood out: In a shocking sign that shows how much the nuclear security landscape has been turned on its head, this past week, a member of Japan’s prime minister’s office who advises Prime Minister Sanae Takaichi on national security told reporters that Japan “should possess nuclear weapons.” These remarks came just months after Japan commemorated the 80th anniversaries of the Hiroshima and Nagasaki bombings.

Whether the world has already entered a new nuclear age marked by renewed arms racing is up for debate. But nuclear affairs have made a strong and undeniable comeback on the front pages of many newspapers this year—something unseen since the end of the Cold War. Even in Hollywood, film directors are daring to talk about nuclear risk once again with a plethora of new and upcoming releases, including this year’s much-remarked A House of Dynamite.

When it reconvenes in January, let’s hope the US administration comes back to the present and sets about a new start in nuclear arms control and diplomacy.

Of course, I couldn’t close this year-end review without mentioning the passing of way too many important figures from the nuclear nonproliferation and arms control community, including Bob Alvarez, Dick Garwin, Dan Hirsch, R. Rajaraman, and (late last year) Evgeny Velikhov. Each stood in their own way for the reduction of the risk from nuclear weapons and pushed for the diplomatic and science-based disarmament or arms control solutions that have been at the core of the Bulletin’s mission since 1945.

Here are five Bulletin nuclear stories that stood out in 2025—and that you should read.

How Fukushima’s radioactive fallout in Tokyo was concealed from the public By François Diaz-Maurin In this investigative piece, I tell the story of how very high concentrations of insoluble cesium microparticles were found in Tokyo following the Fukushima nuclear power plant accident in March 2011, and how these findings were kept from the public’s eye for years. The piece was published as part of a special issue honoring the many contributions of Rod Ewing, a longtime member of the Bulletin’s Science and Security Board who passed away last year, to the science and policy challenges of nuclear materials.

Nuclear expert Jon Wolfsthal on the costs of US nuclear weapons programs spiraling out of control By François Diaz-Maurin In an interview with the Bulletin, nuclear expert Jon Wolfsthal explains how the Defense Department’s inability to meet budget and schedule requirements and to prioritize strategic investments could force instability by default. “To the extent that we will need nuclear weapons to be credible until we can achieve some more stable outcome, we need to make sure we are not wasting money and spending these funds and scarce resources on programs that aren’t going to build what they are designed to build,” Wolfsthal says. “Unfortunately, that’s pretty much what we are doing right now. We are not only trying to build an aircraft while we are flying it. We’re trying to build an aircraft while it’s doing a nosedive into the ground, and the trajectory is already set.”

The United States may destroy the Fordow enrichment plant. It won’t make the Iranian nuclear threat go away By Richard Nephew Before the United States attacked Iran on June 20, former director for Iran at the National Security Council, Richard Nephew, warned that an attack against Iran’s existing nuclear sites—even if successful—would not be enough to eliminate the odds of a future Iranian nuclear breakout. “The United States and Israel must acknowledge that Fordow is not the only pathway for an Iranian nuclear weapons program. Iran may have other centrifuges available, including at secret sites, and probably already at work,” Nephew wrote.

Iran can still build nuclear weapons without further enrichment. Only diplomacy will stop it By Edwin Lyman After President Trump announced the US military had attacked Iranian nuclear sites at Fordow, Natanz, and Isfahan, the world’s attention immediately shifted to answering two questions: How did the US attack unfold? And how much damage had the Iranian uranium enrichment facilities sustained from the attack? The news coverage focused on these questions for several days, during which US administration and military officials offered conflicting statements fueled by a leaked intelligence assessment about the actual damage to the facilities. But one important question was completely overlooked: Could Iran still build the bomb without these facilities? In this article, the director of nuclear power safety at the Union of Concerned Scientists, Ed Lyman, explains how Iran’s stockpile of 60-percent enriched uranium could be used directly to make crude nuclear weapons without requiring further enrichment—an operation that some Iranian groups could do even without state approval.

Eighty years and 89 seconds: It’s time to fight against midnight By Alexandra Bell As the Bulletin celebrates its 80th anniversary this month, the Bulletin‘s new president and CEO, Alex Bell, reflects on the reasons why the current nuclear landscape appears so bleak and offers a refreshing take on how to seriously approach the future of nuclear nonproliferation, arms control, deterrence, and disarmament. “Progress will only be achieved through plodding, frustrating, and iterative steps underpinned by scientific endeavor and sustained political will, some of which can be easily controlled and some of which cannot,” Bell writes.