I don't know if the US had any culpability in 9/11, and I frankly don't care.
Before 9/11 nobody was care about Muslims that much. Then 9/11 came and
all most Christians started to hate Muslims. The propaganda against muslims is going on since 9/11. The perfect excuse for the US government to start bombing Muslim countries and start the "arab spring". Clean the Muslim countries Government that don´t listen to the US Government and place their own man as leaders. Get Oil cheap or or free.
People do not care about Iraq, Afghanistan and so on because that are Muslim countries and Muslims should get killed all because they did 9/11. Thats the logic of most people. A perfect plan from the USA. And besides they can controll all and every human on the world because they want to avoid another 9/11. What a perfect plan.
9/11 cost 3000 mostly American lifes. The consequences from 9/11 in Iraq and Afghanistan cost about 3.000.000 lifes. And it seems like that is not enough.