The third alternative
With Baathist opposition shooting them, and US troops shooting them by mistake, how many Iraqis do you think will be standing in line for a chance to become a member of the all-Iraqi security force?
If the Americans weren't so exhausted from extended tours of duty, there would, IMO, be fewer "friendly fire" errors. If we had friendly, or at least co-operative, back-up from a wider coalition, the extended tours might be less necessary. Also, there would be more people available to train the Iraqis in security/police work.
To make the third option more of an option, we could use the support. As it stands now, we don't have it.
Regards--
Mary Anne