OS Hardening

I’m new to QNX and need to know if the operating system can be hardened to comply with department of defense requirements.

Well departement of defence as many standard depending on the task to be perform. It`s not the same to have an OS in a fighter jet then on you a system that perform off line analysis for example ;)

I beleive QNX6 as not been approved for flight usage. But you should really talk to QNX sales about this.