Objective 1: Stop Fuel
You start off on the mast, quickly climb down and lie down. Slowly move towards the edge of the roof, use the SMG to kill the 2 people in the control booth. Then climb down the 2nd ladder, clear the area, open the gate by using the computer in the booth, move out and run in direction of the tanks. Here kill the guy in the booth, open the gate and kill the few guys in that area. Use two valves to stop the fuel.
Objective 2: Place The Transmitter At The Rocket
Use the elevator to get to the top of the rocket. Simply place the transmitter here. Until you do that there is hardly any resistance, but two snipers in your back.
Objective 3: Bring In The Arms At The Rocket
Bringing in the arms is not the hard part but surviving the masses of enemies that now target you after placing the transmitter. Grab the Sniper rifle from the dead sniper at the top of the rocket and try to kill as many soldiers on the ground as possible. Some of the enemies already began to climb up the stairs towards you, so be careful here too. Now start your way down. Make sure you always walk on solid surface, as soon as you walk over the grate, the enemies might shoot you from below. So make your way down to the three arms, bring them in, then run down the stairs as soon as there is no more resistance. Make sure you use the mini gun as heavy weapon.
Objective 4: Lock The Bunker
Time is a bit of a factor in this mission so run down the tower, cross the green over to the bunker, eliminate the guy in the booth, go in, open the grate and run to the left of the bunker. Here use the code lock, as soon as the door opens go in and directly turn left again, you'll see another code pad, use it. Make your way up, eliminate the 1st troops coming at you. On the left side of the structure there is a lever, use it.