Or, we could have invaded the real enemy, Saudi Arabia and Pakistan.
The goal of every Islamo-fascist is to recreate the Caliphate. In that regard, Mecca, Medina and Islamabad are sideshows. The heart of the Middle East is Iraq and the heart of Iraq is Baghdad. So if we wanted to prevent Al Qaeda from achieving its goal, we did the exact right thing by invading Iraq and having troops stationed in and around Baghdad.
Put simply: No Baghdad, no Caliphate.
Iran first. Iran was and is the proximally most dangerous of them. Knocking off Iran and unlimited fracking in the US and around the world would relegate Arabia to continuous shrinkage.