Getting eliminated sets your streak back to zero. Modern Warfare II additionally offers the choice to use a Scorestreak system instead, using earned score instead of eliminations to track your progress. Again, when eliminated, your Scorestreak progress is reset to zero. Only one Killstreak/Scorestreak within the same category (requiring the same number of eliminations or score) can be selected.
UAV
UAV recon ship that reveals enemy locations on the minimap
Kills: 4
Score: 500
Unlocked: Default
Bomb Drone
A remote-controlled drone with an attached C4 charge.
Kills: 4
Score: 500
Unlocked: Level 18
Counter UAV
A drone that scrambles all enemy minimaps.
Kills: 5
Score: 625
Unlocked: Level 6
Cluster Mine
Throw a device that launches a cluster of smaller mines within the immediate area.
Kills: 5
Score: 625
Unlocked: Level 9
Care Package
Call in a random killstreak care package to your location.
Kills: 5
Score: 625
Unlocked: Level 13
Precision Airstrike
Call in twin jets for a precision strike along the best available path.
Kills: 6
Score: 750
Unlocked: Level 22
Cruise Missile
Control a long range cruise missile with boost capabilities.
Kills: 6
Score: 750
Unlocked: Default
Mortar Strike
Signal several waves of mortars to attack a location.
Kills: 6
Score: 750
Unlocked: Default
Sentry Gun
An automated turret that scans for nearby enemies, and fires incendiary based rounds.
Kills: 7
Score: 875
Unlocked: Level 26
SAE
Call in a trio of jets to release aerial explosives onto specified targets.
Kills: 7
Score: 875
Unlocked: Default
VTOL Jet
Releases a pair of precision bombs before circling back and guarding a location of the player’s choice.
Kills: 8
Score: 1000
Unlocked: Level 35
Overwatch Helo
An escort helo that will watch over your position, and ping nearby enemy locations before engaging them.
Kills: 8
Score: 1000
Unlocked: Level 40
Wheelson-HS
Remote controlled amphibious vehicle with auto sentry capabilities.
Kills: 8
Score: 1000
Unlocked: Level 32
Stealth Bomber
Call in a bomber that releases a large line of explosives along its path.
Kills: 10
Score: 1250
Unlocked: Level 53
Chopper Gunner
Control an assault chopper armed with a turret and air-to-land missiles.
Kills: 10
Score: 1250
Unlocked: Level 27
Emergency Airdrop
Call in 3 random killstreak care packages to your location.
Kills: 10
Score: 1250
Unlocked: Level 42
Gunship
A heavy assault gunship equipped with a laser tracking missile, along with the standard 40mm and 25mm cannons.
Kills: 12
Score: 1500
Unlocked: Level 48
Advanced UAV
An untargetable orbital UAV that reveals the enemy’s direction on the minimap in real time.
Kills: 12
Score: 1500
Unlocked: Level 51
Juggernaut
Juggernaut assault gear delivered by care package. The minigun will drop when the Juggernaut dies.
Kills: 15
Score: 1875
Unlocked: Level 55
Mass Guided Bombs (Nuke)
Call in a game-ending nuke and take the win. 5 Guided missiles spread out across the map.
Kills: 30 consecutive gun kills