Okay, let me try to explain this one more time. In the starbase store, unless they have changed it since I last looked, you can buy Duty officers either as "random" which is any of the 7 "departments" which is 500/per, or a specific class for 750/per white. These are military/engineering/medical. A military doff can give you either any of the specializations within either the security or the tactical departments. They are two different "departments" so if the new system switches it over to being you need x tactical officers, you still can't just buy "tactical" officers from the Doff store on the starbase, but rather "military" officers with a random chance of being either "tactical" or "security" with all the random sub-specializations which will not matter now.