1. “The National Security Strategy of the United States of America,” September 2002, p. 15, http://merln.ndu.edu/whitepapers/USnss2002.pdf.

2. Eric Schmitt and Thom Shanker, Counterstrike: The Untold Story of America's Secret Campaign against Al Qaeda (New York: Times Books, 2011), p. 51.

3. U.S. Department of Defense, “Quadrennial Defense Review,” February 6, 2006, p. vi, http://www.defense.gov/qdr/report/report20060203.pdf.

4. QDR, p. 49.

5. Schmitt and Shanker, p. 180.

6. Glenn H. Snyder, Deterrence and Defense: Toward a Theory of National Security (Princeton, NJ: Princeton University Press, 1961), p. 16.

7. Elaine Sciolino and Don Van Natta, “For a Decade, London Thrived as a Busy Crossroads of Terror,” New York Times, July 10, 2005, http://www.nytimes.com/2005/07/10/international/europe/10qaeda.html?pagewanted=all.

8. Jon Ronson, Them: Adventures with Extremists (New York: Simon and Schuster, 2002).

9. “Blair: World Slept After 9/11,” CNN.com, July 26, 2005, http://www.cnn.com/2005/WORLD/europe/07/26/london.politicians/index.html.

10. James Brandon, “The Next Generation of Radical Islamist Preachers in the UK,” Terrorism Monitor 6, no. 13 (June 2008), http://www.jamestown.org/single/?no_cache=1&tx_ttnews[tt_news]=5013.

11. John Roth, Douglas Greenburg, and Serena Wille, “National Commission on Terrorist Attacks Against the United States: Monograph on Terrorist Financing,” http://govinfo.library.unt.edu/911/staff_statements/911_TerrFin_Monograph.pdf.

12. Robert F. Trager and Dessislava P. Zagorcheva, “Deterring Terrorism: It Can Be Done,” International Security 30, no. 3 (Winter 2005/06): pp. 87–123.

13. Daniel Byman, Deadly Connections: States that Sponsor Terrorism (New York: Cambridge University Press, 2005).

14. George W. Bush, “Statement by the President in His Address to the Nation,” September 20, 2001, http://www.washingtonpost.com/wp-srv/nation/specials/attacked/transcripts/bushaddress_092001.html.

15. “Remarks by the National Security Advisor, Stephen Hadley, to the Center for International Security and Cooperation,” Stanford University, February 8, 2008, http://merln.ndu.edu/archivepdf/wmd/WH/20080211-6.pdf.

16. Caitlin Talmadge, “Deterring a Nuclear 9/11,” The Washington Quarterly 30, no. 2 (Spring 2007): pp. 21–34, http://www.twq.com/07spring/docs/07spring_talmadge.pdf.

17. On the connection between threats and promises in deterrence, see Thomas Schelling, Strategy of Conflict (Cambridge: Harvard University Press, 1960), p. 12.

18. Efraim Benmelech, Claude Berrebi, and Esteban Klor, “Counter-Suicide-Terrorism: Evidence from House Demolitions,” working paper presented at UCSD IGCC Terrorism Research Conference, San Diego, CA, June 27, 2009.

19. Thomas Schelling, interview with the author, Zurich, Switzerland, November 2009.

20. James Poniewozik, “The Banality of bin Laden,” Time, December 13, 2001, http://www.time.com/time/nation/article/0,8599,188329,00.html.

21. Bobby Ghosh, “Inside the Mind of an Iraqi Suicide Bomber,” Time, June 26, 2005, http://www.time.com/time/magazine/article/0,9171,1077288,00.html.

22. Lloyd De Vries, “Turks Bust Alleged Qaeda Plotter,” CBS News, December 19, 2003, http://www.cbsnews.com/stories/2003/12/17/terror/main588982.shtml.

23. Andrew Buncombe, “U.S. Pilots Trained to Shoot Down Hijacked Planes,” The Independent, October 4, 2003.

24. Scott Shane and Eric Lipton, “Passengers’ Quick Action Halted Attack,” New York Times, December 26, 2009, http://www.nytimes.com/2009/12/27/us/27plane.html?scp=1&sq=Scott%20Shane%20and%20Eric%20Lipton,%20%E2%80%9CPassengers%E2%80%99%20Quick%20Action%20Halted%20Attack&st=cse.

25. Daniel Williams, “Egypt Gets Tough in Sinai in Wake of Resort Attacks,” Washington Post, October 2, 2005, http://www.washingtonpost.com/wp-dyn/content/article/2005/10/01/AR2005100101293_pf.html.

26. Susan B. Glasser and Walter Pincus, “Seized Letter Outlines Al Qaeda's Goals in Iraq,” Washington Post, October 12, 2005, http://www.washingtonpost.com/wp-dyn/content/article/2005/10/11/AR2005101101353.html.

27. Thomas Schelling, Arms and Influence (Yale University Press, 1967).

28. Rick Hampson, “25 Years Later, Bombing in Beirut Still Resonates,” USA Today, October 18, 2008, http://www.usatoday.com/news/military/2008-10-15-beirut-barracks_n.htm.

29. Oliver Burkeman, “America Signals Withdrawal of Troops from Saudi Arabia,” The Guardian, April 30, 2003, http://www.guardian.co.uk/world/2003/apr/30/usa.iraq.

30. “National Strategy for Counterterrorism,” June 2011, http://www.whitehouse.gov/sites/default/files/counterterrorism_strategy.pdf; “National Security Strategy,” p. 12.