While the indirect creation of terrorists is certainly also a factor, the direct method of creating plots that you can then "foil" has been widely documented and analyzed:

http://www.wenatcheeworld.com/news/2007/may/11/paid-fbi-info...

http://politicalscience.osu.edu/faculty/jmueller/absisfin.pd...

http://politicalscience.osu.edu/faculty/jmueller/since.html

http://www.techdirt.com/articles/20120917/05193620404/fbi-co...