Anyone with half a brain can see what the real point was behind invading and occupying Afghanistan and Iraq was. It's because they surrounded Iran and the US wanted air bases so they could bomb the shit out of them if the need arose. Now they can just drone them into oblivion from Saudi Arabia and Turkey if needed so Iraq and Afghanistan are a pointless waste of resources.
They could've avoided the emergence of ISIS if they didn't deliberately keep the iraqi government weak, corrupt and useless but the Saudis wanted to ensure the planned Iran, Iraq, Syria oil and gas pipeline could never challenge their own supply of resources so the US did what they were told and the sunni Saudis funded ISIS to keep shia Iraq and Syria on their knees.