That's an easy one. They did not gage it right. They though they could depose a leader they helped create, and then simply let the rest of teh structure operate normally until a new leared was appointed/elected. They did not think the entitre civil structure would dissapear so quickly, or that there was still so much religious devotion in teh Suni and Shia natives (they though the despotic leader had crushed that). they did not do their research properly, they only looked for what would validate doing it. they wanted a foothold in the middle east where they did not have to worry about political disposition (Saudi/Israel) or pay to keep them afloat (Afghanistan). They THOUGHT this would be perfect. They did not think enough, therefore, it was stupid. They should have devoted the same effort to Afghanistan and finished it. Strengthened relations with Turkey, then applied pressure to Iraq. The way we did it just cost too much time, money and lives.