Combo of fog of war and super thick fog made for no fun where I was. 
I had that problem the previous time I tried this mission, Fishercat. The fog was so thick, I couldn't see
anything. The enemy AI could see me, even hundreds of yards away, but I never saw an enemy the entire time I stuck with the mission (which wasn't long). I ended up just shooting at the red square when the leader set a target (which he couldn't even see himself, but would show up on the map).
However, the last time I played this, I was part of the diver team with PapaReap and DTRAX. That was a
lot more fun. For some reason, the fog wasn't bad at all in the city. I could actually
see the people I was shooting at. I don't know why the fog was so much less there, but if you ever play the mission again, I
highly recommend joining the diving team!
Bill