There are 4 stationary guns and 6 heavy targets. Watch my video to see how you can deal with it.
Blow up 1st vehicle with machine-gun. Run to the left, take grenades and Camouflage. Wipe out 2nd Wraith with grenades and go up.
When you'll see 3rd vehicle, distract it using Camo and kill it with M-gun. That's your second to achievement.
Run left to next one stationary gun and blow up 4th Wraith coming from the north.
Run north and throw grenades in 5th vehicle.
North again and there will be last M-gun and 6th Wraith. Kill it.
P.S. Sorry for my English :)