Why do ballistic missile warning radars need much greater range than aircraft-detection radars?

Ballistic missile warning radars require significantly greater range than aircraft-detection systems—often reaching 2,000 to 3,000 nautical miles compared to approximately 200 nautical miles for aircraft—due to the extreme speed and nature of ballistic missile threats.1

These systems must detect and track targets at much longer ranges to provide sufficient time for command centers to calculate trajectories and issue alerts. Furthermore, ballistic missile reentry vehicles often have a very low radar cross section, making them much harder to detect than aircraft.21

Beyond simple detection, these radars must perform complex battle-management tasks. They are required to reliably distinguish actual warheads from "confusion targets" such as decoys, chaff, and debris. Because these objects may have different physical properties, the radar must measure the velocity of all detected items to identify which are heavy warheads and which are lighter decoys that decelerate more rapidly due to atmospheric drag. To achieve this, ballistic missile defense radars utilize significantly higher transmitter power—often 100 times greater than aircraft-detection radars—and large, sophisticated phased-array antennas.13