GoKawiilRecent global conflicts, from Russia and Ukraine to Iran and Israel, have seen a resurgent awareness of the frailty of US munitions stock, which has been drawn down by both direct and indirect involvement in these events. While exact stockpile volumes are not disclosed, it is estimated that supplies of US warheads and the missiles that carry them have declined by nearly an order of magnitude since their peak during the Cuban Missile Crisis. Analysts have estimated that in the event of a conflict in the Pacific between China and Taiwan, US munitions supplies could be depleted in as few as three days, with some higher-tier terminal-phase missile supplies potentially depleted in the first 24 hours of conflict.
This was a foreseeable problem. Advocates for deterrence have supported expanding munitions stockpiles and accelerating production timelines for decades. While improving technical performance (precision and range) is useful, increasing attritable mass, or the volume of munitions that can be produced and pointed at a target set per year, is the actual measure of credible deterrence. And we have a critical bottleneck problem.
Historically, the decline of US munitions production capacity has been attributed to the bottleneck imposed by solid-rocket motor (SRM) casting, which only a handful of US companies are authorized to perform as of May 2026. The limitation on expanding solid rocket motor production is not inherent to the motor mechanics, but rather the fuel these motors use for power: ammonium perchlorate (AP). AP is the oxidizer that enables high-performance SRM in the inventory, bound with powdered aluminum (fuel) in rubber to form a controlled explosive. This fuel is cured inside motor castings for multiple days in heavily regulated environments designed to prevent cracks or voids in the cured grain that can cause the motor to over-pressurize and explode.
The handling required for AP not only limits SRM production but also the production of AP itself. In the period following the Cold War, there were two primary AP producers in the US, the Kerr-McGee Chemical Corporation and the Pacific Engineering and Production Company of Nevada (PEPCON). On May 4, 1988, an explosion generated by some subset of the 9 million pounds of AP at the PEPCON chemical plant in Henderson, Nevada, caused a large fire, eventually killing two people and injuring 372 others. As of May 2026, there is now only one US producer of AP, the American Pacific Corporation (AMPAC) in Cedar City, Utah.
Because AP serves as a fundamental bottleneck to expanding SRM supply, new entrants to the munitions space won’t necessarily improve the US’s munitions production capacity, even if they are more nimble startups with more efficient processes. In fact, the opposite can be true: more demand for AP means there is less to go around, limiting production for any one company. A munitions base in which a single AP-plant accident can halt national missile production is more fragile than any other major military capability. Resolving this bottleneck by building a second, independent propulsion supply chain should be a strategic priority for the US defense sector.
One primary option for resolving this dependency is expanding scaled production of liquid-propulsion missiles, which are powered by widely available hydrocarbon fuels, high-test peroxide, and advanced engines adapted from commercial counterparts. In this piece, we outline how the missile supply chain became so brittle and why pursuing liquid propulsion is likely the best route to rebuilding a national munitions stockpile with a realistic timeframe and budget.
The Origins of Solid Propulsion
Missile fuel is a binary: it can either be solid or liquid. The choice of fuel governs a meaningful share of downstream decisions about how missiles are built and operated, including how motors are constructed, how missiles are armed for launch, and whether missiles can be shut down or throttled in flight. At the start of the US ballistic missile program in the 1940s, liquid propellants were used exclusively until the development of sufficiently performant solid propulsion fuels in the 1960s. In the decades since then, the US has transitioned to using only solid propulsion missiles, due largely to safety issues with early liquid technologies.
Liquid Propulsion Systems
Liquid-fueled missiles like the Atlas and Titan I, which were the first intercontinental ballistic missiles designed and built in the US, used cryogenic propellants such as liquid oxygen oxidizer (LOX) with RP-1 kerosene fuel. LOX boils at -183 °C, meaning it could not be stored in the missile itself because it boils off continuously and embrittles seals. On launch order, the sequence to prepare a LOX missile required 10-20 minutes before launch:
... continue reading