It shouldn't be any damn war prior to 2000. It should be called:
Call of Duty: Modern Warfare 2
Just like how Rainbow Six went in order, but restarted with Rainbow Six: Vegas and is continuing with Rainbow Six: Vegas 2.
They should make it a continuation, or a whole new story where you got to Iraq or something. Just keep it modern for f**k sakes. Keep the same modern guns and add a few new ones like the C8 Assault Rifle.
Also have more teams in Multiplayer you can choose from (as opposed to a random one out of Spetnaz, SAS, Marines, Op For) such as Canadian forces, US forces, terrorist, SAS, Russian Forces, french...whatever!!
Keep the same set of maps (or even remove a couple crappy ones like Bloc and Countdown) and add some more cool maps.
Rant done.
To sum it up: Make it Call of Duty: Modern Warfare 2, and keep it the same with minor changes and a new story/war.