Defense Platform Vulnerability Assessment: Quantifying Rare Earth Supply Chain Risks Across Major Weapons Systems

The United States defense industrial base faces an unprecedented strategic vulnerability arising from its critical dependence on rare earth elements (REEs) for advanced weapons systems, combined with China's near-monopolistic control of global REE supply chains. Despite controlling only 38% of global REE reserves, China dominates 68.75% of REE mining, 90% of processing capacity, and 99% of heavy rare earth element (HREE) processing—materials essential for the permanent magnets, guidance systems, and electronic warfare capabilities that define modern military superiority. The Herfindahl-Hirschman Index (HHI) of 4,954 for global REE processing indicates a highly concentrated, monopolistic market structure far exceeding the 2,500 threshold for concern. This quantitative study addressed a critical gap in defense planning by developing and applying a composite vulnerability assessment framework to evaluate REE supply chain risks across 15 major U.S. weapons systems spanning five platform categories: Air (F-35 Lightning II, F-22 Raptor, B-21 Raider, KC-46 Pegasus), Naval (Virginia-class submarine, Columbia-class submarine, DDG-51 destroyer, CVN-78 carrier), Ground (M1 Abrams, JLTV), Munitions (Tomahawk, JDAM, AIM-120 AMRAAM, Patriot), and UAV (Predator/Reaper). The vulnerability index formula V = w₁(REE_content) × w₂(element_criticality) × w₃(1-substitutability) × w₄(strategic_importance) × w₅(1-stockpile_coverage) was applied across three disruption scenarios: Graduated Export Restrictions, Complete HREE Embargo, and Conflict-Induced Supply Cessation. Results revealed naval platforms exhibited the highest category vulnerability (M = 0.7814), with the CVN-78 Ford-class carrier ranking most vulnerable (V = 0.915), followed by Columbia-class (V = 0.793) and Virginia-class submarines (V = 0.743). Ground platforms demonstrated the lowest vulnerability (M = 0.370). Element criticality emerged as the strongest vulnerability driver (r = 0.91), while stockpile coverage provided the strongest protective effect (r = -0.93). Scenario analysis demonstrated that mean platform vulnerability increased from baseline (M = 0.608) by 6.3% under graduated restrictions, 12.2% under HREE embargo, and 22.5% under conflict-induced cessation. These findings provide defense planners with an empirically-grounded framework for prioritizing supply chain mitigation investments, informing strategic stockpile decisions, and guiding industrial base policy to enhance national security resilience. Keywords: rare earth elements, supply chain vulnerability, defense platforms, critical minerals, national security, China, permanent magnets, strategic materials, quantitative risk assessment