Are you talking about the one where you are in the tower and you have to take out the guys trying to out the bridge as well as you spotting the tanks for airstrikes? If so...you just can't stay in the tower...once the tower gets hit by the tanks move over to the other side of the street and keep moving and looking through your binoculars...its can be done and it took me about 6 times to get through that mission...but its certainly not the toughest mission...