Complicated, yes; but we aren't that omnipotent, such that we get to take full credit (blame) for the situation.
And really, other than informing present strategy, who did what, and when, and to who, doesn't matter now. Not what the Brits did a 100 years ago, or who we backed 20 years ago.
Dang, we did team up with Stalin when it served our needs against the Nazis; If you concede that some kind of stability in a region so important to our economy is within our legitimate interests - who would you have chosen?
The lesson to be learned is that this stuff is complicated, and no one will get it right all the time. Maybe not even most of the time. To my mind, an ascendant Iran, with nukes, and visions of empire, might have made Saddam not look so very bad, in comparison.
After the fact, and naive, analysis leaves me cold - evil people are behaving badly, to the detriment of our interests. It's legitimate to use whatever advantages we own, and that suit the need, against them.
Not gonna be a neat, complete, and total solution. Never perfection, just halting progress, some regression on occasion, and Karma almost never has anything to do with it.