Most people are focusing on security in the comments, but I think that's missing a more important point. First, all developed-nation military forces have inter

Most people are focusing on security in the comments, but I think that's missing a more important point. First, all developed-nation military forces have internal, "secure" tactical and strategic communication networks for classified (e.g. Secret, Top Secret) data. So something like WhatsApp, Signal, Telegram, or Threema would only be used for unclassified, administrative communications as others have already mentioned. But there are still controls required for unclassified, administrative communications. Speaking as a US military officer who works in IT, we have to think about data ownership and retention for things like investigations and compliance with FOIA requests. It's impossible to do that if everyone is using personal accounts on communications services that we don't control. I'm not sure how much control the Swiss government can exert over Threema, but it's presumably more than they can control services hosted outside of their borders. This article from last summer explains why the US Defense Digital Service Director got in trouble for using the Signal app for official business: https://www.nextgov.com/cio-briefing/2021/06/defense-digital-service-director-used-signal-violation-pentagon-policy-ig-says/174879/ https://www.nextgov.com/cio-briefing/2021/06/defense-digital...