I know personally that given the choice I'd probably rather use Signal than whatever messaging system the DoD contractors managed to come up with. And private conversations between senior military officials over encrypted DoD communication channels probably aren't FOIAable anyway.
Both are fairly "meh" WRT to usability, but neither are so awful people should be breaking the law over it.
They have a completely sepearate internet for TS/SCI (JWICS https://en.wikipedia.org/wiki/Joint_Worldwide_Intelligence_C...)
Yes, in the chat where a reporter was accidentally present, many of the messages were set to be disappearing. I don't know why anyone would do that if not to avoid recordkeeping laws.
> The images of the text chain show that the messages were set to disappear in one week.
https://apnews.com/article/war-plans-hegseth-signal-chat-inv...
Further, Project 2025 suggests bypassing federal record keeping legislation by simply holding in-person meetings without record.
https://www.youtube.com/watch?v=xxe55mU4DA8
Oddly, the Project 2025 training videos that presumably the members of the executive cabinet have seen say _not_ to delete messages or set messages to auto-deleting _because_ that would be in violation of federal record keeping legislation.