If Iraq fires on US forces with chemical weapons, the US will be blamed for brining it on ourselves. Never mind that Iraq doesn’t have chemical weapons.
If Iraq fires missiles (conventionally armed or otherwise) at Israel, the US will be blamed for forcing it to kill Israeli citizens. Never mind that Iraq is no longer a serious threat to its neighbors.
If Iraqi citizens are killed because of Iraqi chemical or biological attacks against US forces, the US will be blamed for causing the deaths of innocents. Never mind that Iraq doesn’t have the weapons.
If Iraqi forces in US or UK uniforms brutalize Iraqi citizens, many will believe the ruse and the US will be blamed for the war crimes. Never mind our history of usually helping those in war-torn regions and Saddam’s history of killing his own people.
If terrorists strike against Americans, either in the US or abroad, the US will be blamed for bringing the death and destruction upon itself. Never mind that we are attacking a military target with military forces and terrorists attack civilian targets with suicide bombers.
If, after the war, we uncover huge piles of proscribed weapons, illegal programs, and terrorist links, the US will be blamed for creating and staging evidence to indict an innocent enemy. Never mind the entire history of Iraq’s deception and secrecy concerning it’s weapons programs.
Many people will blame America for everything that goes wrong and will not believe the evidence and witnesses afterwards. That doesn’t mean they’re right. But don’t be surprised. I’d rather be right than popular.