The United States is the undisputed global military superpower. With an annual defense budget approaching USD 900 billion, Washington spends more on defense than the next nine countries combined—including China, Russia, India, Germany, South Korea, the United Kingdom, France, Saudi Arabia, and Japan. The U.S. is also the world’s largest arms exporter, controlling nearly 44% of the global weapons market, while home to some of the world’s largest defense contractors: Lockheed Martin, Boeing, Raytheon Technologies (RTX), Northrop Grumman, and General Dynamics.
Yet, despite this immense military might and technological prowess, America’s defense-industrial complex currently faces a perilous vulnerability: its supply of a critical heavy rare-earth metal, samarium, used in fifth-generation stealth fighter jets like the F-35 and in precision-guided missiles such as Tomahawks, hinges on a decades-old, abandoned samarium stockpile in France.
This precarious dependence highlights the fragility of U.S. defense supply chains and exposes a strategic vulnerability in one of the country’s most advanced military sectors.
Samarium, a rare-earth element, is primarily used in the production of samarium-cobalt (SmCo) permanent magnets—high-performance magnets essential to modern defense systems. Invented in the 1960s through pioneering research by Karl Strnat at Wright-Patterson Air Force Base and Alden Ray at the University of Dayton, SmCo magnets offer exceptional resistance to demagnetization, strong magnetic fields, and high-temperature stability.
These magnets became critical components in a wide range of defense applications, from aircraft and satellite systems to missile guidance and control technologies. In many ways, the development of samarium magnets positioned the U.S. at the forefront of high-performance materials technology.
Yet, despite its early lead in samarium processing and magnet production, the U.S. gradually ceded control of this vital supply chain. By the 1980s, the production of samarium magnets had largely shifted to China, driven by multiple factors: the country’s rich rare-earth deposits, minimal environmental regulations—processing samarium is highly polluting—and generous state subsidies.
Over subsequent decades, China’s dominance only grew. Today, it mines nearly 60% of the world’s rare-earth metals and controls almost 90% of rare-earth magnet production, effectively cornering the market on SmCo magnets.
The strategic consequences of this supply concentration became apparent earlier this year. In retaliation for U.S. tariffs imposed under President Donald Trump, Beijing imposed strict restrictions on the export of certain rare-earth magnets, particularly heavy rare-earth magnets like samarium-cobalt. While some light and medium rare-earth magnets were later exempted from restrictions, the heavy rare-earth category remained tightly controlled.
In April 2025, China began requiring export licenses for samarium and six other rare-earth metals, effectively choking the supply for U.S. defense contractors. Recognizing the urgency of this vulnerability, the U.S. Geological Survey listed samarium as the “No. 1 critical mineral at highest risk of supply chain vulnerabilities” in its proposed 2025 Critical Mineral List.
Had the supply of samarium been cut entirely, production of essential U.S. defense systems—including fighter jets, missile systems, and satellite components—could have ground to a halt.
Fortunately for the U.S. defense sector, a decades-old stockpile of samarium in France provided a crucial lifeline. New York-based Arnold Magnetic Technologies, a subsidiary of Compass Diversified and a key manufacturer of samarium-cobalt magnets with facilities in Switzerland, Thailand, and China, had a supply of samarium sufficient to last just over a year.
Aaron Williams, Arnold’s chief commercial officer, described the situation as precarious. “When China announced export controls on April 4, our supply was sufficient for a year,” he said. “But as months passed, it became clear that more long-term solutions were urgently needed.”
Arnold turned to UK-based Less Common Metals (LCM), one of the last remaining Western rare-earth manufacturers. LCM, in turn, contacted Solvay, a Belgian chemical company and former leader in rare-earth oxide production. Remarkably, Solvay still maintained a factory in France with a stockpile of samarium from decades prior—abandoned when the company deemed rare-earth separation in France “uneconomical” due to high costs.
The stockpile, estimated at around 200 tons, was sufficient to meet the U.S. defense industry’s annual demand for approximately one year. Less Common Metals transported the samarium to Britain, where it is refined into metal and alloys, which are then shipped to U.S. factories to produce magnets for use in fighter jets and missile systems.
An Nuyttens, president of Solvay’s GBU Special Chem division, emphasized the strategic importance of the partnership: “We are very pleased to partner with LCM and Arnold Magnetic Technologies to provide essential resources for high-performance applications, particularly in the strategic domain of the European aerospace industry.”
To further ensure long-term supply security, LCM was acquired by U.S.-based miner USA Rare Earth on November 18, 2025, in a move aimed at vertical integration. By controlling both the source and processing of rare-earth metals, U.S. companies hope to mitigate future vulnerabilities.
While samarium sourced outside China is significantly more expensive—five to eight times higher than Chinese prices—the U.S. defense industry is willing to absorb the cost. The priority is securing a stable and reliable supply, even at a premium.
For now, the U.S. defense sector is confident that new sources of samarium will be found before the French stockpile runs out. Additionally, China may eventually ease its export restrictions, but the experience has underscored a critical lesson: reliance on a single, geopolitically sensitive supplier for a strategic resource is untenable.
The U.S. reliance on the French samarium stockpile highlights a broader issue within defense supply chains. Even a superpower with unmatched military capabilities can face vulnerabilities when critical industrial inputs are concentrated in a single foreign country.
The samarium case also illustrates the broader consequences of decades-long industrial decisions. By offshoring rare-earth production in pursuit of lower costs, U.S. companies unwittingly created a supply dependency that now threatens national security.
Experts warn that this is just one example among many. “Supply chain vulnerabilities are becoming a growing concern across the defense industry,” said Jack Lifton, co-chair of the Critical Minerals Institute. “We cannot afford to repeat past mistakes with other critical materials, from lithium and cobalt to specialty alloys.”
For now, the U.S. has bought itself a reprieve. The collaboration between Arnold Magnetic Technologies, Less Common Metals, and Solvay has kept the defense-industrial complex running, ensuring that fighter jets, missile systems, and other high-tech defense capabilities continue to operate. But the underlying lesson remains clear: strategic resources, even in an era of unmatched military dominance, cannot be taken for granted.
The French samarium dump serves as a temporary lifeline, but it is also a stark reminder of the fragility that can underlie even the most powerful defense-industrial complexes. As the U.S. looks to the future, the challenge will be to rebuild domestic and allied supply chains for critical materials, reducing dependence on any single foreign actor—particularly one with a history of leveraging resources as a tool of geopolitical influence.
In the words of Aaron Williams of Arnold Magnetic Technologies, “Once burned, twice shy. We will be extremely cautious in the future, avoiding reliance on any one country for critical minerals.”
The story of the U.S. defense industry’s survival on a decades-old stockpile of samarium is both a cautionary tale and a testament to ingenuity under pressure—a reminder that even the most powerful nations can be brought to the edge by the vulnerabilities hidden deep within their supply chains.
