Why? because signals intelligence. Because the only ones on Earth that can intercept a signal without being found out is the US military and the National Security Agency. They are the end all be all of interception of radio transmission, phone transmission and digital transmission. No other nation has that kind of power maybe with the exception of Russia and maybe Israel. Not even the British, French or even China can intercept signals and use it as intelligence like the military and NSA. See Space Force.