I'd recommend reaching out to @BenBalter to talk through using this for DoD. As for FISMA and compliance I believe GitHub has a government-ready ToS that could

I'd recommend reaching out to @BenBalter to talk through using this for DoD. As for FISMA and compliance I believe GitHub has a government-ready ToS that could be applied - but you'd probably want to get an official go-ahead to use it to host code, and I'd still think hard about using GitHub vs. a git service behind the firewall depending on what you're building.