Killstreak Rewards are special bonuses that can be acquired by killing a certain amount of enemies in a row without dying. You can lower the required amount by 1 with the Hardline perk.
Modern Warfare 2 expands the killstreak system from Call of Duty 4 and World at War. You have 3 killstreak rewards that you can customize to your liking. You start off with the UAV, Care Package and Predator Missile. As you reach level 10 and beyond, you earn points which you can use to unlock the rest of the killstreaks in any order you choose.
Killstreaks stack up, meaning that you don't lose a UAV after gaining, for example, a Predator Missile. Stacked up killstreaks can't be used as pleased, instead they need to be used in the order you've acquired them.
All killstreak kills (Predator Missiles, Airstrikes, etc.) count towards your next killstreak, except for those that have been acquired from Care Packages. All killstreaks that have been earned during previous lives will not add to your total.
* The Pave Low is currently glitched.
Description: This deploys a UAV (unmanned aerial vehicle) that shows enemies on the radar for 30 seconds. Multiple UAVs (from the same team) makes the refresh rate faster.
Description: Airdrops a random killstreak or ammo. If you can't get to the high level killstreaks on your own, use this. Just throw the red signal flare and wait for the helicopter to drop the package. The package can be stolen by anyone, even by your team mates, so be careful!
Description: Scrambles the enemy radar for a short period of time, even if they don't have a UAV in the air.
Description: Airdrop a placeable XM312 Sentry Gun. A helicopter will drop the weapon, which you can pick up and place anywhere you want. The Sentry Gun (box) can be stolen by anyone, just like the Care Package, so be sure to pick it up straight away. You can move the Sentry Gun around even after you've deployed it, but it won't fire until it's placed.
Description: Allows you to remote control a Predator Missile to the ground. Your screen will change to an overhead view and you have approximately 5 seconds to control the missile to your target. You can give the missile a boost to make it go down faster.
Description: This is much like the Airstrike from Call of Duty 4, but this time you can control the direction of the Airstrike for more accurate kills.
Description: Airstrike with a hovering harrier. The selected area gets bombed, after that a hovering harrier will guard the area for 45 seconds and tries to kill all nearby enemies. It can also attack enemy helicopters.
Description: Deploys a Attack Helicopter to the map, just like in Call of Duty 4. It will circle around the map and automatically attack enemies for 60 seconds.
Description: Calls in a cargo plane that drops 4 Care Packages.
Description: Calls in a heavily armored attack helicopter (Sikorsky MH-53 Pave Low) to patrol the map for 60 seconds. It works just like the Attack Helicopter, but it has twice the armor and two turrets.
Description: Calls in a Stealth Bomber (B-2 Spirit) to carpet bomb the selected area. You can also control the direction, just like with the Precision Airstrike.
Description: Be the gunner of an attack helicopter. Your screen changes to the gunners view and the helicopter will fly around the map. The helicopter flies around for 40 seconds before it leaves, which does not include the time it takes to travel to the map.
Description: Be the gunner of an AC-130 Gunship. Your screen changes to the gunners view and the AC-130 will fly around the map. You have 40 seconds to use the 25mm, 45mm and 105mm guns to shoot at enemies, but you can also take down enemy helicopters and harriers.
Description: The electromagnetic pulse (EMP) temporarily disables enemy electronics for 60 seconds. It also stops the enemy from calling in killstreaks, and at the same time drops down any helicopters and aircrafts that are in the air.
Description: Calls in a nuclear strike that kills everyone on the map. It gives you and your team an instant win.