We are not dealing with an analagous situation here. The folks we are battling are not the armed forces of a government, legitimate or otherwise. They are fanatical civilians whose only desire is to kill as many infidels as possible to ensure their place in paradise. There is no central figure, like the emperor, who can order them to lay down their arms and make nice. If such a figure did emerge he'd be killed by the more fanatical factions and the war would go on.
Honestly, there really is only one way to combat these guys and the West has no stomach for it. If they didn't think they were going to paradise after they died, then they wouldn't try to get themselves killed. The only thing that might stop them would be the threat they'd end up with something unclean after death -- being fed to dogs or pigs, being buried with bodies of the latter, etc. The ACLU and those with more heart than sense would raise such a stink as to make such a notion stillborn. Simply killing these guys isn't the answer, because that is what they want -- and it does inspire others to take up the cause (c.f., the Palestinians).