Defending Against Cheap Drones Costs 15-35x More Than Attacking With Them

The cost exchange ratio in modern missile defense has reached unsustainable levels. During Middle East operations in 2024-2025, U.S. and allied forces routinely used SM-2 missiles ($2.2 million each) and SM-6 missiles ($4.3 million each) to shoot down drones costing as little as $20,000-$50,000. PAC-3 MSE interceptors at $3-5 million each were expended against ballistic missiles costing a fraction of that amount. Analysis of UAE defense spending against Iranian-sponsored attacks found that for every $1 Iran spent on drone attacks, the UAE spent $15-35 on air defense -- a ratio that makes sustained defense economically impossible over time. This matters because it inverts the traditional military calculus where the defender has the advantage. If an adversary can force a defending nation to spend $35 for every $1 of offense, they can win through economic attrition without ever achieving a military breakthrough. An adversary need only keep launching cheap drones and missiles in sufficient quantity to exhaust the defender's interceptor stockpile and defense budget. Senior Navy and Defense Department officials described this dynamic as 'unsustainable' by mid-2024, yet U.S. forces continued expending top-tier interceptors against low-end threats throughout 2025 because no affordable alternative was available in theater. The problem cascades beyond immediate cost. Every SM-6 fired at a Houthi drone is one fewer SM-6 available for a high-end contingency against China's anti-ship missile arsenal. Every THAAD interceptor used against an Iranian ballistic missile is one fewer available for North Korean scenarios. The opportunity cost of using premium interceptors against commodity threats depletes readiness for the most dangerous scenarios the U.S. faces. The structural reason this cost asymmetry persists is that the U.S. missile defense architecture was designed during an era when the primary threats were sophisticated ballistic missiles from peer adversaries, not swarms of cheap drones and crude rockets from non-state actors. The entire interceptor development pipeline -- from requirements definition through testing to production -- is optimized for exquisite, expensive, high-performance systems. Programs like directed-energy weapons (lasers) and counter-drone systems promise to close the cost gap, but none are deployed at scale. The Navy's HELIOS laser system and the Army's DE-SHORAD program are years from full operational capability. Until affordable kill mechanisms are fielded at scale, the U.S. military is trapped in a lose-lose dynamic: expend expensive interceptors and go bankrupt, or withhold them and accept hits. Adversaries understand this arithmetic perfectly and are building their strategies around it.