You should anticipate the negativity and long faces and the liberal mantra that the US "put" Saddam in and supported him.
My advice: just smile and say nothing.
That's the best retort to your liberal family members. It'll drive them crazy.
If they believed it to be true, then simply state that the US corrected the problem. Unlike the mistake made by Jimmah Carter allowing the overthrow of the Shah. How about the Democratically controlled congress pass a law to eradicate Iran's theocracy.
That is the manner I've taken when around ultra-lib family members. When I had to listen to inane spoutings-off about how Pres. Bush was the worst pres in history because he would not see "Brokeback Mountain" (yes, this was a real concern to them), I just sat back silently with a smile. Of course, I was steaming mad on the inside, but never let it show.