There is no evidence on who was behind the sept. 11 'surprise' attacks, in fact there has been no investigation whatsoever thanks to the Bush administration.
Moreover, there has been no evidence at all supporting the U.S. government's terrorist conspiracies:

Sept 11: No evidence that Al-Qaida was behind it, nor did Al Qaida claim responsibility as they do. Still a mystery.

Taliban: No evidence that the Taliban was responsible for Sept. 11 or that they were protecting Bin Laden or that Bin Laden was in Afghanistan. No reason for invading. Very vague explanations not clear.

Iraq: No evidence that Saddam had "weapons of mass destruction" or has connections to Al-Qaida or that he sponsors terrorism. No reason for invading. Explanations very vague not clear and constantly changing. The regime is not much different to many third world political systems and their history with close U.S. relations.

Whose next? North Korea? Iran? Syria? Cuba? Colombia?

Every country should have the right to defend itself. If the U.S. has a nuclear capability then there is no reason why any country should not have it. Furthermore, every country should have the right to self-determination and no nation should interfere with any other nation's internal conflicts. The only conspiracy that seems to be plausible is that the CIA has been behind it all since Sept. 11. In fact, the CIA have been terrorizing the world since that organization was formed. It is worth noting that prior to sept. 11 the U.S. economy and its position in the world was deteriorating (Euro, European Union, Germany, Japan, Brazil, Venezuela, China, anti-globalisation protests, national liberation movements: Nepal, Colombia). For the far right in Washington, sept. 11 changed all that as the "war on terror" policy would justify its imperial legacy once again, with the help, of course, of its loyal attack dog Britain.