First off, the two tanks arent difficult. in fact, they are very easy to deal with. JUST WALK AROUND THEM.
When you get the mission to blow up the bridge, simply take the C4 that is a bit infront of you at the X and run down the right side of the town. You will be able to by pass most of the soliders in the town. When you get to the end of the building on the right, youll see the first bridge and the first tank.
Pull out your meds and run. If you get hit, take the meds and run down under the bridge. The tank will start shooting at you while you are under there if you run up and down the hill you just went down. In fact, for me the tank destroyed the bridge for me.
AS for the other, i ran under it, dropped a c4 under it and blew the second up. Sure you can do this with the first.
Other tips for playing this on hard. Find the GOL in the beggining village. A sniper has it on a 2 story building on the right. Keep it. Makes this map, especially the very end, very easy.
Also, keep the laser designator to kill the chopper. If you target the chopper when it stops, just assume its going to move towards you and pre move the missle closer to the bottom of the screen. really easy to hit. and since you had your sniper rifle all the guards getting to the helipad were easy to kill.
EASY. on Hard.