system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Top-level government direct exchange is often said to proceed via a 'secure line' - how is such a line secured?
gpt
It varies of course but usually it involves something like end to end military grade encryption and only moving the call over infrastructure which is difficult for a listener to compromise, such as military communications satellites or secret fiber optics cables. There is no such thing as communication that is impossible to intercept and decode but it can be made impractically difficult.