With a certain amount of ranks, you are able to unlock any of the one kill streaks on the list, even the nuke.
At first, you start out with UAV, care package, and predator missile.
3 kills - UAV
4 kills - Care Package
4 Kills - Counter-UAV
5 kills- Sentry gun
5 kills precision air strike ( you call in a direction airstrike)
7 kills - harrier strike( an airstrike with a hovering harrier that attacks the selected area for 30? seconds.
7 kills - helicopter
8 kills - emergency air (drop drops 4 packages of ammo or kill streaks)
9 kills - pave low (more powerful helicopter)
9 kills - stealth bomber (airstrike that's not on the map)
11 kills - chopper gunner (pilote a chopper)
11 kills - ac 130 (pilote an ac 130)
15 kills - emp ( disable all electrionics, uav, thermal, etc)
25 kills tactical nuke ( end the game with a complete win.