The US political class knows the heavy Saudi involvement, but everyone has to kiss the Saudi's ass.
Even the Saudi's hubris let's slip sometimes, like when Saudi and Canada had a little spat, one of hte Saudi orgs tweeted a pic of a plane flying towards the CN tower:
If true, it is impossible to escape the conclusion that powerful elements within the US government and intelligence apparatus were and are complicit in the 9/11 attacks and that they were, effectively, an inside job.