As Iranian-designed Shahed drones proliferate across battlefields from Ukraine to the Middle East, relatively cheap unmanned aircraft are forcing the use of some of the world's most expensive air defense systems, raising questions about the long-term sustainability of that approach.

The issue has taken on new urgency in the wake of Operation Epic Fury, as Iranian drones — widely estimated to cost $20,000 to $50,000 to manufacture — target U.S. forces and allied Gulf states across the region.

U.S. and partner forces have relied on a mix of Patriot missiles, Terminal High Altitude Area Defense batteries, naval interceptors and other systems to blunt the attacks.

While many of the incoming drones have been intercepted, the strikes have still exacted a cost, killing six U.S. service members in Kuwait and damaging civilian infrastructure, including airports and hotels in the United Arab Emirates and Bahrain.

The mounting toll has intensified concerns over how to counter drone swarms without depleting interceptor stockpiles that cost millions of dollars each to replace.