Because that is what the book is about. Specifically, about the history of the Islamic Center of Munich, regularly attended by Mahmoud Abouhalima, the 1993 WTC bomber, and Al Qaeda co-founder and bin Laden mentor Mamdouh Mahmud Salim. I don't know what you are trying to imply. As suggested previously, read the book.
"Because that is what the book is about." Is your intention to promote a book? I thought it was to make a point was about US alliances and supporting for terrorists and other unsavoury types going back a long time.
That argument would only be stronger if you left it broad by including US support for Catholic Guatemalan dictators and Italian fascists, Protestant White South Africans, Orthodox fascists during the Greek civil war or useful nazis generally. These all predate 1957 but instead you single out Muslim groups to make a more narrow point? I'm just wondering if you have something against Muslims.
