According to the author, what was one cause of the terrorist attacks in the late 1990s and early 2000s in the nonfiction book, How to Hide an Empire?

Saudi Arabia is mentioned in the final chapter of the book, before the conclusion, in connection with the U.S. need for oil and its entanglements with Osama Bin Laden, himself a member of a wealthy and elite Saudi family. Immerwahr implies that the terrorist acts against the United States in the late 1990s and early 2000s were, in part, the consequence American involvement abroad.