If I tell you to walk down a street that is dangerous, am I morally culpable when you get mugged? After all, I didn't mug you. The muggers did.
I agree with the people who say that the muggers are morally culpable than the person who gave the directions--rather, the ones who say that the chap who engages in ethnic cleansing or sets off a car bomb in a crowded marketplace is morally worse than the US.
But I don't agree with those who say that we are therefore absolved of all responsibility. Our invasion created the conditions in which bombings, kidnappings, and so forth that weren't taking place before, now are. It seems ridiculous to me to say that we have no responsibility for the innocent people who have been terrorized by these thugs.
This is not an argument over whether we are bad or not. It's an argument over whether we have any responsibility for mitigating the bad results of our actions. I'd say we obviously do. Taking in some of the people who have been forced to flee the violence seems like a no-brainer.