I don't think they 'washed their hands' of the affair of Saddam's trail - from the outset it has been the stated intention of America and Britain to 'free' Iraq to govern itself - so leaving Sadaam's punishment in the hands of the Iraqui government is in keeping with that stated ideal.
That said, even now Bush refuses to admit, even from his experienced military advisers, that the situation in Iraq is one which cannot be resolved by more troops and further force.
The fact that he keeps on regurgitating his sickening soundbites like "staying until the job's done .." doesn't alter the basic fact - this is our generation's Viet Nam. Jane Fonda was quoted saying exactly that on the news yesterday - and she'd know, she was protesting when it really was this nation's Viet Nam.
History teaches us valuable lessons, but only if you listen to hear what they are.