WW1, WW2, the Middle East, Vietnam, the Balkans, Rwanda, Tibet, Iran-Iraq, Pakistan-India all have one thing in common: they are wars about territories (that one party claims and the other defends).
Because nations (or states) are involved, those wars can be settled and ended with a peace treaty.
I don't see Al Qaeda claiming territories; they are terrorists with killing as many innocents as possible in mind. They cannot be stopped with a treaty.

Saddam isn't going to invade the US (what for, anyway?) ; Iraq is on the other side of the planet.
Even being in possession of a nuclear bomb doesn't help. Most of the time, the enemy is right next doors. Using an atom bomb will hurt the country that had sent it (and its leaders).

Raoul