May I recommend the following? Warning: these are all pdf.
1. Greg Thielmann, who was head of the Office of Strategic Proliferation and Military Affairs in the State Department's Office of Intelligence and Research, has produced "Preventive Military Intervention: The Role of Intelligence" for the University of Pittsburgh's Ridgway Center for International Security Studies.
Yes, I am a member of the same working group and am supposed to prepare a similar short and readable policy brief, based on my chapter for the forthcoming book.
It needs to be done ASAP. Yesterday.
Disclosure, continued: Greg helpfully went over the last draft of my chapter and provided useful detail. Don't worry, members of the Human Subjects Committee, he did this as a colleague, not as a subject of my research.
2. Ohio State Political Science Professor John Mueller has authored "A False Sense of Insecurity?" about the relative unimportance of terror threats. It was published by the Cato Institute, a libertarian think tank in Washington, DC.
3. Michigan Senator Carl Levin (D) has produced "Report of an Inquiry into the Alternative Analysis of the Issue of an Iraq-al Qaeda Relationship," October 21, 2004.
Levin looked into the Pentagon intelligence operation directed by Doug Feith, a potentially illegal undertaking, as I've blogged before.
I extend thanks to Matt Yglesias who helpfully provided the link.
Update: I fixed the link to Thielmann's piece, thanks to an alert reader (and former student).