Two possibilities:
1. they didn't want to be saved in the first place, or
2. they don't have the courage needed to have their own country.
Either way, if they aren't willing to help with the protection of the Americans, they will lose the Americans, who will go home and never be heard of again.
And we didn't help ourselves in the previous conflict by listening to the UN and pulling out before the job was completed.
How many ways can we reassure the true Iraqis we're here to stay? So that they will come forward quicker to help save themselves.