Iran appears to be using shortwave radio to send cyphered messages. It's an old school Soviet method of communication. And guess what? It works. None of it goes through a computer, so there is nothing to hack. It's inexpensive & easy to do, & you can just keep changing frequencies when your opponents start interfering with the one you're using.
All the fancy spy equipment the US has? Not meant to deal with that simple, low-tech tactic.