While there seems to be logical reasons to involve intelligence agencies from outside the US in an operation of this kind (e.g. other country's operators might not be so squeamish with regard to actions that kill Americans). It is extremely premature to try to identify whether people or organizations outside the US might have been involved, what exactly that involvement might have been (lead, assist, look-the-other-way), and what they might expect in return. First, we need to get to the point that a strong majority of Americans understand that the "9/11 Commission Report" is a cover-up of crimes against humanity. Once that occurs, perhaps prosecutors can begin the court-dominated investigations needed to find out exactly who the criminals are. Justice at the level of local prosecutors, judges, and jurors is a lot more difficult to control. That's why so much effort has been made from day-one to avoid anything about 9/11 going to court.