ALBUQUERQUE, N.M.—On an expanse of desert here between a Netflix studio and self-storage facility, construction is under way on a fusion plant meant to help America win an escalating nuclear-arms race.

By the decade’s end, its developers say, the site will be home to a nuclear-fusion facility designed to subject weapons parts to the sorts of stresses they would experience in an all-out nuclear blast.

Testing with fusion reactors helps ensure America’s nuclear weapons still work after decades in storage, components are reliable and that new designs will have the desired effect, without resuming the explosive nuclear tests of decades prior.

At the Albuquerque groundbreaking ceremony, the site was mostly dirt, punctuated by a pair of Deere excavators holding up an American flag. Keith LeChien, chief technology officer of three-year-old startup Pacific Fusion, said it wouldn’t be barren for long.

“We’re watching what China’s doing and how fast they’re going in fusion,” he said. “We’re staying ahead of that."

Keith LeChien, Pacific Fusion co-founder and chief technology officer, at the company’s factory in San Leandro, Calif.

The project marks a new era in America’s nuclear posture. Once completed, Pacific Fusion’s facility will produce more than 1,000 times more fusion power than the government-operated machine that was put into service for weapons experiments after the U.S. stopped underground blasts in 1992.

The startup’s design creates all that energy by linking together 156 modules, or movable shipping container-sized machines, that each emit pulses of energy. It is building them at its San Leandro, Calif., factory.

The reactor will help serve the Trump administration’s goal of maintaining and modernizing nuclear weapons that have been in storage for decades, as well as designing and producing new ones, something that was anathema to prior administrations. Motivating this are Russia’s nuclear threats to the West and China’s fast-track to nuclear parity.

We are entering now a very complex time where we have to be postured to deter two near-peer adversaries,” said Paul Dean, vice president of the nuclear policy program at Nuclear Threat Initiative, a Washington nonprofit that works on reducing nuclear threats.

The Trump administration has reversed Obama-era prohibitions on pursuing new nuclear warheads or capabilities. The New START Treaty, which had put constraints on Russian and U.S. nuclear weapons development, expired in February without a replacement. No arms-control agreement exists with China.

A pulser module at Pacific Fusion's factory in San Leandro.

A technician works on the pulser module.

"Without some guardrails around those relationships, we have the potential to have an unregulated arms race,” Dean said. “It’s starting to become a pretty dangerous era.”

Russia retains the world’s largest arsenal—around 4,400 weapons to the U.S.’s roughly 3,700. Beijing is aggressively building out the infrastructure, including fusion plants much like the one under way in Albuquerque. China has tripled its stockpile in a decade to around 650 weapons, built 320 new missile-launching sites in the desert and is constructing research centers that analysts say will be more advanced than the U.S. national labs’ ignition facility.

Sam Wurzel, a fusion-energy researcher who formerly worked for the Energy Department, was at the Albuquerque event. Gesturing toward the plot where Pacific Fusion’s facility would one day be, he said, “Yes, this is a good start. But at the end of the day, China has serious industrial capacity and industrial policy around fusion."

Just over a month prior, China had test-fired a submarine ballistic missile with a dummy nuclear warhead with the capacity to reach the U.S. from Chinese coastal waters, raising alarms across the Pacific region.

The missile launch is shown in an image released by Chinese state media. Li Xiangchao/Xinhua/Getty Images

The U.S. has accused Beijing of surreptitiously performing experiments that violate a global testing treaty the two nations have signed, but not ratified. President Trump now wants to do the same, saying in a Truth Social post in October that if adversaries are flouting rules around weapons testing, the U.S. ought not be restrained. Absent a resumption of underground blasts, which Energy Department officials say they don’t want, fusion-reactor testing provides the most valuable data.

Brandon Williams is administrator of the National Nuclear Security Administration, or NNSA, which is part of the Energy Department and the office responsible for the country’s nuclear stockpile. He said his office is focused on continuing to provide new strategic weapons options for the president, including novel designs.

“Deterrence is never static. It’s what our adversaries are doing that drives us to push us forward,” Williams said in an interview. “We have to keep moving."

The Energy Department’s chief spokesman said the agency was ensuring U.S. capabilities had parity or exceeded other nations. “At the direction of the president, the nation’s nuclear enterprise is undergoing massive modernization efforts.” A White House official said Trump wants to engage China in arms-control talks. (The Defense Department didn’t comment.)

A spokesman for the Chinese Embassy in Washington called on the U.S. to “make drastic and substantive cuts to its nuclear arsenal” and stop using threats as a pretext for a weapons buildup. “China never engages in a nuclear arms race with any country,” said spokesman Liu Chang. “Our efforts to modernize our nuclear forces are intended to safeguard national strategic security and uphold global strategic stability.”

Pacific Fusion, backed by around $1 billion from venture capitalists, is the first private nuclear-fusion company to have a memorandum of understanding with the NNSA. It calls for a range of technical collaboration but doesn’t involve any funding. This year’s draft defense-spending bills from both the House and Senate call for the NNSA to partner with private companies to advance its nuclear weapons work, building on a similar effort last year.

Systems producing high-yield fusion expose weapons parts to intense heat, radiation and pressure nearly synonymous with a nuclear blast—hotter than the sun at more than 100 million degrees Celsius—without any explosions. Using supercomputers and artificial intelligence, scientists gather data from the tests that informs how weapons components hold up, how the warhead will perform and what needs to be done to make them more reliable, more precise or deadlier, scientists said.

A technician at Pacific Fusion works on the cathode, which goes inside the pulser module.

Pacific Fusion’s LeChien said he expects its facility, built with cheaper and off-the-shelf components, to be the world’s first to produce high-yield fusion. A Chinese state-backed fusion facility with similar power potential is set to break ground this month.

High-yield is a critical threshold for weapons testing, but producing a viable commercial energy system to power neighborhoods or cities, which Pacific Fusion is also pursuing, is expected to take several more years. Weapons testing provides an attractive near-term business opportunity for those whose fusion reactors can serve in that task.

That prospect—and the Trump family’s interest in the sector—have propelled private investment in nuclear fusion higher since the start of 2025, with $2.2 billion invested so far this year, according to PitchBook data. 

Late last year, Trump Media & Technology Group, the parent company of the president’s social-media platform, merged with nuclear fusion company TAE Technologies in a $6 billion deal. TAE has said it would break ground on its first commercial fusion plants this year, but no date has been set.

Defense Department official Elbridge Colby has called for more small-blast nuclear weapons as part of a new strategy, officials said. The Navy is working on its first tactical nuclear warhead since the 1980s. Scientists at the Energy Department said they are preparing for the possibility of conducting new experiments that will mirror China’s.

“There is no limitation on what you can do now,” said Hans Kristensen, director of the nuclear information project at the Federation of American Scientists, a scientific nonprofit that works to reduce threats of global catastrophe, including nuclear war. The U.S. has “swung back to what is fundamentally a revitalized nuclear-weapons production enterprise."