Call of Duty: Modern Warfare 2/Homeland Security

Walkthrough
This mission can be soloed, but it helps to have two players in-case one of you goes down.

Start off by picking up an AK-47 Grenadier and going to the alleyway behind the diner, camp in one of the alcoves, shooting any enemies that come through the door or hide behind the cars. When the first Wave is over, pick up an RPG and collect ammo for it, you will not need it on the second wave, but on the third a helicopter comes. In wave 2, a predator drone fires missiles at you if you are outside, stay in the alcove and you will be fine. After you have killed all of the enemies in this and the next wave, there will be a helicopter left, hide in the diner and use the RPGs, the AT4 or just shoot it down if you feel it will be easier. If you really have trouble, there is an ammo crate outside. In the next wave there will be a BTR, sometimes the predator missile destroys this but usually you will have to shoot it with an RPG, as long as you stay out of its sight, it is fairly easy. Use all the previous tactics in the final wave to win.

Option 2: At the start grab the claymores and the first sentry gun on the tarp. There are two sentry guns you can set up. Place one in the backside of the diner behind the barricades with the PDF (Primary Direction of Fire) towards the gas station. Inside the diner is the other sentry gun, place it behind the counter with its PDF out the front of the diner. Grab the SAW off the counter, it's an efficient way to take down the helicopters. Set up claymores at the entrances. Save your RPGs and AT4s for the armored vehicles and helicopters. You can also draw the Predator Drone's fire out front of the diner to eliminate foot mobiles if you get overwhelmed.

Note: there are also turrets in CRB Financial and on the roof of Nate's but they are hard to get to without two players as the covering fire from the second player is beneficial, there is a lot of risk with going into the open on harder difficulties and as these turrets are not required, it may be best to leave them or go in-between waves.

Secret: There is a third turret hidden on the roof of the building across the road.

Wave 1

 * 20 Hostiles

Wave 2

 * 30 Hostiles
 * Predator Drone armed with Missiles

Wave 3

 * 40 Hostiles
 * 1 Helicopter
 * Predator Drone armed with Missiles

Wave 4

 * 30 Skilled Hostiles
 * 1 BTR80
 * Predator Drone armed with Missiles

Final Wave

 * 40 Skilled Hostiles
 * 1 BTR80
 * 2 Helicopters
 * Predator Drone armed with Missiles