It's interesting when I see empty vacuous phrases like "the cause of 9/11" thrown around.
Let's look at what lead up to 9-11 that might have involved the US.
Iraq invaded a neighboring Nation State and the US was asked to help free that Nation State, stationed troops in Saudi Arabia to do that with the full support of the Saudi Government and under mandate from the United Nations to free Kuwait.
After a long period of attempted negotiation to try to avoid a battle, it became clear that there was no chance for peaceful resolution, invaded to drive back Iraq forces from Kuwait.
After a short battle the US and its allies succeeded in freeing Kuwait and showed restraint by NOT continuing on to overthrow the government of Iraq or attack major Iraqi cities and infrastructure.
Again, under UN mandate, supported and maintained a quarantine of Iraq to prevent the ruler of Iraq from carrying out his threats against the surrounding Nation States.
Where are the asserted "criminal acts"?
Anyone so limited that they can only spell a word one way is severely handicapped!