The initial war was justified and necessary; Saddam Hussein was a threat to everyone around him, and had shown absolutely no sign of wanting to work with the international community in any way. The Iraqi people wanted him removed, but lacked the power to do so.
The subsequent handling of the peace was massively botched by a series of political blunders and an attitude that the Iraqi population was 'the enemy' from the occupying American troops. Constant attempts to pull out prematurely and to 'punish' Iraqis for wanting to be shown respect within their own country resulted in an irretrievable quagmire.