If defense systems have to shoot three, four, or five Patriot interceptors to knock down one drone, the cost becomes 15, 20, or $30 million per $20,000 drone.

Patriot missile systems, costing a million dollars per missile, are experiencing "leakage" as cheap Iranian drones (costing $20,000-$50,000) are getting through.

Iran is producing drones for about $30,000 a piece.

Each Shahed drone costs between 20 and 50 grand to manufacture, built with off-the-shelf commercial electronics.