They should not be using cell phones at all if security is a concern not to mention they are a distraction and can be used against people when they are captured. The enemy will extract ones family details from the phone and call them. Let the psychological games begin. No applications are required, just turn on the cell phone and one is instantly a target.<p>Encrypted freq hopping wide spectrum dynamic power radios with encrypted repeaters managed by the military on the field is the only semi-secure option and even that comes with significant risks. Even then there should be little to no voice comms. Just a 4 byte group designation and a 2 byte code burst that maps to per-arranged tactical instructions and optional coordinates. Ack codes should be optional in the event the enemy gets the decryption key of the hour. Manual ack should have the option of commands received or squad compromised.
It's kind of surprising that they managed to convince so many people it is secure. I think part of it is that the people who really care about this sort of thing never bothered with it since it requires a phone number.<p>XMPP has signal style encryption with OMEMO now. Just use that.
Is that because it's not made by/in a NATO country and, therefore, no NATO nation can coerce the developers to install a back door (like, say, the NSA could with Signal)?<p>Personally I'll stick to Wire, Threema, and my own Matrix server instance.