As to the first, for centuries, perhaps millenia it has been known that when you repress a people with brutal regimes, you create a reaction in type, in fact driving that population towards the more extreme elements among them. Hence, yes, the imperialist power and its puppet governments bear some of the responsibility for radicalizing the resistance.
As to the second, you don't find your defence of U.S. policy somewhat tainted by first the support of Hussein, then the removal of his regime? First the support of Noriega, then his capture? By the support of Bin Laden against the Soviet Union? By the CIA organized murder of Allende leading to the installation of Pinochet? By the death of in excess of 3,000,000 people in Southeast Asia during the Vietnam era?
They should be blamed for those actions and many more and if that all seems like business as usual to you, then there isn't much point.