If we were going after the people responsible for 911 we should have invaded Saudi Arabia. And, when we first went into Afghanistan we had zero evidence that Bin Laden was behind it. It wasnt until months later that we found some tapes in a house over there that slightly implicated Bin Laden. The real reason we went into Afghanistan is for the pipeline, and for that reason we will never leave.
As for Iraq, we were responsible for Sadam invading Kuwait. We could have stopped it but instead encouraged him to invade just so we could crush his army for Israel. The second invasion was an in-your-face ridiculous war.