After all hell breaks loose and you gain control of your character, go to the SAM and get inside. Your goal here is to just get a lock on and shoot down drones until you inevitably get knocked out of the SAM. Once you get out of it, run forward and you have a choice to either provide sniper overwatch, or rappel down with the group.
If you rappel down, you'll be fighting some enemies on ground level. If you provide sniper cover, you'll be armed with the Storm PSR rifle. This rifle has piercing capabilities, as long as you hold the fire button down and the meter on the right is full; each fully powered shot takes 5 ammo, though. Take out every enemy you can see, including two on the roof on the right side.
Once you take out most of them, you will rappel down to meet with the rest of the group. When you're on the ground, take out any enemies lingering around, then go to meet with everyone else. There should be a MG truck ahead, so take those out and then get in the vehicle.
When you're behind the wheel, push the pedal to the metal and just keep going through any enemies and their vehicles. You will want to go on the left side when you can, then the right as soon as possible, hugging the right wall. Once you get to the police escort, keep going straight until a scene plays out.
After getting control again, you will be pitted against a lot of enemies, as well as a CLAW. You can get access to some Quadrotors in the Access spot inside the overturned vehicle on your right; you can use these to destroy the CLAWs. Once the first is destroyed, kill any other enemies that appear and go forward until a second CLAW shows up. Take care of this one, as well as the enemies in the building behind it, then go to the marker.
Continue going forward, opting to go through the building on your left, instead of through the outside area. There will be some enemies inside here, so take cover and take them down one by one. Once you exit the building, be careful of the guy with the RPG in an adjacent building, so be quick to shoot him.
Once it's clear, go down the stairs and into a big open area. There will be quite a few enemies here, including two MG trucks off in the distance. It's best to use the Storm PSR here, so you can see where they are located. Once it seems clear enough, go to the marker and a scene will play out.
When the scene is over, just run forward to the FA-38 and you'll be able to enter it. Once you get the hang of the controls, you will need to follow the van that Harper is in. You will begin moving more when you get to the President, who you have to protect. The biggest threat here will be the helicopters, with vehicles on the ground as second priority. You're able to only lock onto one things at a time, so definitely keep an eye out for helicopters.
Keep going until you see some drones fly by, which will trigger your aircraft to begin speeding up and going after them. This part can be challenging, since you're moving pretty fast and the drones like to go low and in between buildings. Couple this with the fact that there is a boundary that you cannot leave, otherwise it will reset you back to the last checkpoint. Just keep flying after the drones and shooting them down, one by one with the rockets. After three rounds of them, the mission will be over.
