Why have the American leaders still not been brought to task for war crimes against the Iraqis?

If there were war crimes by soldiers they were dealt with in the US military courts. The leadership has not committed war crimes as they have ordered the military to take extraordinary caution and limit civilian casualties. I would suggest that they try Al-Qaeda and the most vicious insurgent groups of m murder and war crimes as they have been doented to have violated the Geneva Convention and human rights accords numerous times.