Start off by going around the corner and shooting the guard before he can respond, then either hit the guard circling the sniper tower from afar, or rush him. Then you can go near the outer stairway and hit the guard before he even spots you. Run up the sniper tower and grab the sniper rifle. From the tower you can hit one of the two guards standing in the tunnel with ease, then you need to hit the other guard while he is running toward you. Run into the tunnel.
Then you need to run to the next sniper tower; shooting anyone in your way. The tower provides good cover from the two guards in the bunker. You have to kill the guard that circles the sniper tower, the guard that is hiding behind the metal creates to the left, and the guard behind the ammo boxes by the big door before getting the two guards in the bunker. The best way to get the guards in the bunker is from behind looking through the back door at an angle so that only one of them can shoot at you at a time. Open the big doors to get to the next part of the level.
The first priority after opening the second door is getting the guard
on the left wall; he will immediately run to the alarm on the side of
the building summoning two more guards and alerting the two in the
building. After you get that guard, turn around and hit the one
that is patrolling the third sniper tower (he is probably already
shooting at you). You need to destroy the alarm on the side of
the building. There is a guard and a general inside the building
witch you can kill if you want, but they won't even know you are there
if you don't use the KF7 Soviet.
Open the first gate and place
the covert modem on the computer screen behind the building.
Shoot the lock off of the next gate and open it to proceed to the next
part of the mission. From here, there are two strategies you can
try: Covert or Aggressive.
Finish up by jumping of the platform.
Run as fast as you can, don't bother shooting any guards unless it
won't slow you down at all. Shoot the alarms and jump off the
platform. This is good practice for dodging. This is a
fairly simple target time to get, just stay on task and remember
that you don't have to kill everyone.