CBO: Iran War Depleted 2/3 of US Missile Interceptors, $38B Cost

The Congressional Budget Office on Tuesday, Sept. 15, 2026, released its first formal accounting of the U.S. war with Iran, estimating the Pentagon has spent $38.1 billion through Aug. 1, 2026, with likely additional costs of $2 billion to $3 billion for each month the conflict continues. The estimate closely tracks a Defense Department inspector general report published the prior day, which put the cost at $33.4 billion through June 29. Together, the two analyses provide the most comprehensive public picture yet of a war that began Feb. 28, 2026 and has already reshaped global energy prices and U.S. defense readiness. The largest single cost driver is not fuel or operations but the replacement of munitions. CBO estimates the Department of Defense will need $21.7 billion to replace expended weapons through Aug. 1. Of that, missile-defense interceptors account for $13.1 billion, land-attack cruise missiles $7.3 billion, and other munitions $1.2 billion. Increased flying hours added another $10.4 billion, while higher fuel prices contributed $2.7 billion. The report says the war has raised fuel prices around the world since President Donald Trump launched the conflict on Feb. 28, linking the military campaign to rising consumer costs for fuel, food and other goods. Beyond the dollars, CBO warns that the war has consumed between one-half and two-thirds of the U.S. inventory of certain missile-defense interceptors since June 2025. The estimate covers four systems: the Patriot surface-to-air missile, the Terminal High Altitude Area Defense (THAAD), the Standard Missile-3 and the Standard Missile-6. Because the Pentagon does not publicly disclose interceptor inventory levels, CBO analysts compared reported expenditures with the total number of missiles DoD has purchased to estimate depletion. The consumption has been driven in part by U.S. missile-defense operations defending Israel against Iranian attacks, which predate the full-scale war. The result, CBO cautions, is that the United States will have reduced interceptor inventories for several years. The strategic implications are stark. CBO says the depleted stockpile could become especially problematic in a conflict with an adversary that fields large numbers of ballistic and cruise missiles, specifically citing China and a potential conflict over Taiwan. The unit costs alone explain why: CBO estimates roughly $4 million for a Patriot or SM-6 interceptor, $12 million for a THAAD round, and $28 million for a sophisticated SM-3. These weapons are produced at relatively low rates, and CBO estimates rebuilding DoD's interceptor inventory would probably take at least five years, even if production were increased. That means the Pentagon would enter any near-term Taiwan contingency with significantly reduced magazine depth for layered defense. The report was requested by Rep. Brendan Boyle, D-Pa., the top Democrat on the House Budget Committee, and lands less than seven weeks before the Nov. 3, 2026 U.S. election. Democrats are already campaigning against the war and pointing to higher costs for fuel, food and other essentials. Trump has framed the military action as necessary to prevent Iran from developing nuclear weapons and initially predicted the conflict would last only weeks. The new CBO and inspector general figures could intensify that debate, particularly because they provide independent, nonpartisan validation of the war's cost and readiness toll. For defense analysts, the core lesson is about industrial capacity and strategic consumption rates. The United States can outspend adversaries in dollar terms, but the interceptor depletion shows money alone cannot quickly replace high-end guided munitions when production lines are optimized for peacetime rates. The CBO's five-year rebuild estimate is not just a procurement timeline; it is a vulnerability map for a potential high-intensity conflict. If the Iran war continues at the current burn rate, the marginal $2 billion to $3 billion per month may be manageable fiscally, but the depletion of irreplaceable interceptors represents a compounding readiness risk that no supplemental appropriation can immediately solve.