Neodymium and samarium may sound like something from a Hollywood superhero film, but they aren’t. These obscure elements drive modern tech and are buried deep inside modern missile systems, and they give China a quiet yet powerful lever over the United States in the ongoing conflict with Iran.
So-called rare-earth elements—including neodymium and samarium—are essential inputs for high-performance magnets used in fighter jets, navigation, sensors, missile guidance systems and precision components that steer high-speed interceptor missiles such as Patriot and Thaad. Without rare-earth elements, many advanced defence systems simply do not work.
This is where geopolitics meets materials science. China controls 90 percent of the global rare-earth supply chain from mining and processing to magnet manufacturing.
In recent years, Beijing tightened export controls on several rare earth elements and magnet technologies as part of a broader strategy to respond to US-led export controls on advanced chips.
What has received less attention is how Chinese export controls intersect with missile defence. Interceptor missiles are being used at high rates in the recent US-Israeli-Iran conflict, particularly against Iranian ballistic missiles. Interceptors depend on precisely engineered control systems that heavily rely on rare earth magnets. Obviously with interceptors in heavy demand, the US must rapidly scale production to defend Israel and, ideally, its allies in the Gulf.
That is easier said than done.
Analysis by the Center for Strategic and International Studies warns that the US remains deeply exposed to Chinese rare-earth export controls. Despite diversification efforts, the US is struggling to replace Chinese supply, and its defence industrial base already lacks the capacity to scale quickly to meet rising demand.
The challenge is not just access to the raw materials themselves, but the specialised industrial processes needed to transform them into high-performance magnets. In other words, the bottleneck sits in the middle of the supply chain. And the uncomfortable truth: China controls it.
But surely the US has stockpiled enough of these materials to avoid a crisis?
The US does maintain strategic stockpiles. But stockpiles are designed as short-term buffers, not long-term solutions. They buy time during disruptions; they do not solve the underlying industrial problem.
And that problem is scale. These capabilities require long-term investment and cannot be created overnight. In short, the longer Iranian forces continue to fire ballistic missiles, the greater the draw on US reserves which the US may find difficult to immediately replenish in war time conditions.
Even Washington’s recent efforts illustrate the enormity of the task. The US has committed millions of dollars to build secure rare earth supply chains and magnet manufacturing capacity. But new mines, processing plants and magnet factories take years to develop.
Meanwhile, China’s supply chain remains mature, integrated and difficult to replicate.
The result is a vulnerability with no easy answers.
The US and its allies are trying to diversify supply chains through partners such as Lynas Rare Earths in Australia. The US is funding new projects, but building a complete mine-to-magnet supply chain outside China will take years, not months.
That timing matters. If interceptor missiles are being consumed rapidly during the current conflict, US defence contractors may struggle to keep up. Even small disruptions in specialised inputs can ripple through defence manufacturing.
This is precisely why rare earths have become a geopolitical tool in Chinese hands in its strategic competition with the US.
In the lead-up to trade negotiations rounds with the US in 2025, China showed no hesitation in using export controls over rare earths and critical minerals for geopolitical signalling.
That leverage does not need to be exercised publicly. In practice, it may operate quietly through licensing decisions and administrative processes.
The escalating conflict with Iran creates an uncomfortable reality: Beijing is well aware of US defence supply-chain vulnerabilities. Export controls on rare earth magnets is a subtle bargaining chip in the backchannels, reminding the US that its military endurance against Iranian missile onslaught is constrained by Chinese export controls.
None of this means Beijing could suddenly shut down US interceptor missile production. Supply chains are complex, and defence contractors maintain inventories. But the structural imbalance remains.
Missile defence is often discussed in terms of radar, interceptors and strategic doctrine. Yet beneath those systems lies a far less visible contest over control of the critical-minerals and rare-earths processing that make them possible. And in that contest, China currently holds a critical lever to de-escalate the conflict and rein in US militarism.