Fusion power, the dream of generating energy by replicating the sun’s process, is seeing a resurgence in its historical roots—defense applications. The fusion industry began decades ago when scientists sought to repurpose the knowledge from thermonuclear bomb research during the Cold War. While the field has long had ties to national security, these connections are now becoming more prominent as climate-focused venture capital funding slows. In 2022, a major breakthrough occurred at the National Ignition Facility, a lab that has supported defense-related research for over 25 years. The shift toward defense applications is partly due to the high costs of fusion research, which have made venture capitalists look for alternative funding sources. The defense industry, particularly interested in new technologies for modern warfare, has found a natural ally in fusion startups. Traditional air defense systems were built to counter human-piloted aircraft, which are fewer and larger in size. However, the rise of small, inexpensive drones has exposed the inefficiency of such systems. A notable example from a decade ago involved a $3 million Patriot missile used to shoot down a $200 consumer drone—effective but economically impractical. Laser weapons, which can fire quickly and cheaply using electricity, offer a more efficient alternative. Fusion startups, with their expertise in high-powered laser systems, are well-positioned to help develop these weapons. Recently, Xcimer, a laser-based fusion startup based in Denver, announced a partnership with RTX, a major defense contractor that includes Raytheon. Under the deal, Xcimer receives funding from RTX Ventures, while RTX explores using Xcimer’s powerful lasers for its own defense applications. Xcimer currently operates what it claims is the largest privately owned laser system in the world, which it plans to use for developing a fusion-powered electricity plant. The lasers will compress fuel targets to create fusion reactions that release energy. While the current system is not yet powerful enough for a full-scale power plant, it has already drawn interest from the defense sector. Xcimer is not the only fusion startup aligning with defense interests. Pacific Fusion, another startup, recently signed a memorandum of understanding with the National Nuclear Security Administration (NNSA) to collaborate on high-energy-density fusion experiments. The company has begun construction on a demonstration facility in New Mexico, near major national laboratories. While the primary goal is to generate more energy than the facility consumes, the power produced will also be far greater than what the government currently uses for nuclear weapons testing. “It turns out that the facility we’re building also has utility in this world-leading defense application,” said Keith LeChein, a co-founder of Pacific Fusion. The company’s co-founder and COO, Carrie von Muench, emphasized that defense applications have always been a key consideration. LeChein, who previously worked at major national labs, helped develop the core technology that now drives Pacific Fusion’s mission.