Numbers stations are shortwave radio broadcasts that transmit sequences of numbers, letters, or words in formats readable only by someone possessing the corresponding encryption key. They were widely used by intelligence services during the Cold War to communicate with agents in the field without internet or cellular networks — making them harder to trace and immune to digital surveillance. The reappearance of numbers-station-style transmissions in the 2026 Iran context reflected Iranian intelligence using Cold War methods that are difficult to intercept meaningfully without the encryption key.