It essentially was. No matter what you believe happened that day, one thing is for sure: we funded Al Qaeda and Bin Laden to fight against the Soviets. Admittedly, the CIA funded and aided them. Admittedly, the FBI can't hold Bin Laden as a suspect for 9/11, so they don't list that event under his supposed crimes.
Our actions around the world act as a catalyst for extremism, so no matter what you believe, it was absolutely an inside job. Whether the CIA pulled the trigger or not themselves is another story, but they quite possibly could have.