This game is generally quite evil. Sometimes, you are placed just in front of some bazookas (called snipers for some reason), and your entire squad will be wiped 5 seconds in the first time.
I also thought that maybe bunkers are explained in the manual, but no. Bunkers also spew soldiers indefinitely, just like baracks, but you can only destroy them with a turret, not with regular grenades or rockets. And a turret can be destroyed with a single stray rocket or a grenade, so you are running from infinite soldiers to gun down all the rocket soldiers, and you hope that the game didn’t generate any soldiers with grenades (those are random, as far as I can tell).