This is the Third mission in the campaign. Here's How I completed it:
Run straight for the fight control point. As long as you finish hacking it, they enemy will not re-capture it.
Hack the 5 terminals to activate the AA turrets, then kill any remaining enemy's around.
Once you get the checkpoint, deploy a tank. As soon as your tank lands, disregard it and run straight for the missile silo.
Run in the side door closest to you and hack the control point. There shouldn't be any enemy's around. But same as before, as long as you hack it, they will not re-capture it.
As soon as you finish hacking the silo control point, if you have done it under 8 minutes, the achievement will unlock. Remember this has to be done on hard difficulty.