I just completed mission 4 (don't know what it's called, you land on a beach and have to blow up turrets, SAMs and all that stuff, then hack the ComCenter and finally escape by submarine) the third time and on the debriefing screen I realized that there are 4 tertiary objectives in the mission.

I searched for hours, but I only found 3 of them...
- blow up the power plant
- blow up the refinery
- blow up the comcenter after downloading the data

But - what's the 4th one ? Anyone discovered yet ?