Fusion power is circling back to its origins. While startups pursue the dream of feeding the grid, many are also rekindling ties to the defense applications that first sparked the field.
The industry took shape years ago when physicists sought peaceful uses for the science behind Cold‑War thermonuclear weapons. The national‑security link persisted, highlighted by the 2022 breakthrough at the National Ignition Facility—a lab that has served defense missions for over a quarter‑century.
The trend has intensified as climate‑tech venture capital—traditionally a major backer of fusion firms—has slowed. Although fusion startups have secured a sizable slice of recent climate‑tech funding, the technology remains capital‑intensive, making alternative financing attractive to investors.
Defense contractors have long investigated laser weapons, and interest has surged with the rise of drone warfare. Conventional air‑defense systems, built for manned aircraft, are ill‑suited to swarms of small, inexpensive UAVs—illustrated by a case where a $3 million Patriot missile intercepted a $200 hobby drone. The approach works, but it is far from cost‑effective.
Laser weapons change the equation. Rather than expending a costly, single‑use missile per engagement, they can fire rapidly and inexpensively, drawing power from a generator, ship reactor, or engine.
Startups developing laser‑driven fusion reactors are natural allies for directed‑energy weapons programs. Last week, laser‑fusion company Xcimer unveiled a partnership and investment from RTX, the parent of Raytheon. Through RTX Ventures, Xcimer receives funding, while RTX gains access to evaluate Xcimer’s high‑power lasers for defense applications.
Headquartered in Denver, Xcimer claims to run the world’s largest privately owned laser system, which it intends to harness for a future power plant. In that facility, lasers will strike fuel pellets, compressing nuclei to trigger fusion and release energy. Its present system, Phoenix, delivers about a tenth of the power needed for a commercial reactor, yet it is sufficiently robust to have attracted defense interest.
Xcimer is not alone in pursuing defense ties. Last month, Pacific Fusion signed a memorandum of understanding with the National Nuclear Security Administration to collaborate on high‑energy‑density fusion experiments.
Pacific Fusion has broken ground on a test facility in New Mexico, situated near Sandia and Los Alamos National Labs. The plant’s chief aim is to prove net‑positive energy output, but it also serves ancillary roles; the fusion reactions it will produce vastly exceed those used today in the government’s nuclear‑weapons testing program.
“The facility we’re constructing also serves a leading‑edge defense purpose,” said Keith LeChein, Pacific Fusion’s co‑founder and CTO, in a recent TechCrunch interview.
This alignment is deliberate, not accidental. “Defense applications have always been on our radar,” remarked Carrie von Muench, Pacific Fusion’s co‑founder and COO. LeChien, who devised the company’s core technology, previously served at Sandia, Lawrence Livermore, and the NNSA.
Fusion technology has advanced far beyond its early weapons‑program origins, yet its national‑security roots remain relevant. The renewed partnership between the sectors is long overdue and could provide a valuable boost to fusion startups willing to engage.