Best would been to just leave them be with Saddam and his imaginery WMD.
Since this war against terrorism is a huge scale free recruitment office for the terrorists themselves.
but well, US insisted to go in there, even though most of the world said "thats not really a good idea".
So theres pretty much two options:
a) ensure theres enough loyal troops for the iraqi goverment, so the insurgents won't have a chance after US leaves
b) leave now and get even worse fked up reputation in the western world.