¹ Bernhard Lewis, ‘The Roots of Muslim Rage’, Atlantic Monthly, 266 (1990), 47–60, p. 60.

² Giandomenico Picco, ‘The Challenges of Strategic Terrorism’, Terrorism and Political Violence, 17 (2005), 11–16, p. 14.

³ Ahmed S. Hashim, ‘The World According to Usama Bin Laden’, Naval War College Review, 54 (2001), 11–35, p. 29.

⁴ Joseph S. Nye Jr, ‘The Decline of America’s Soft Power’, Foreign Affairs, 83 (2004), 16–20, p. 17.

⁵ http://www.whitehouse.gov/news/releases/2006/09/20060911-3.html (last accessed 6 March 2008).

⁶ Samuel P. Huntington, The Clash of Civilizations and the Remaking of World Order (New York: Simon & Schuster, 1996); Samuel P. Huntington ‘The Clash of Civilizations?’, Foreign Affairs, 72 (1993), 22–49.

⁷ Akbar Ahmed and Brian Forst, eds, After Terror: Promoting Dialogue among Civilizations (Cambridge: Polity, 2005); United Nations, Report of the High-level Group (New York: United Nations Alliance of Civilizations, 2006).

⁸ See Bruce M. Russett, John R. Oneal and Michaelene Cox, ‘Clash of Civilizations, or Realism and Liberalism Déjà Vu? Some Evidence’, Journal of Peace Research, 37 (2000), 583–608; Errol A. Henderson and Richard Tucker, ‘Clear and Present Strangers: The Clash of Civilizations and International Conflict’, International Studies Quarterly, 45 (2001), 317–38; Giacomo Chiozza, ‘Is There a Clash of Civilizations? Evidence from Patterns of International Conflict Involvement, 1946–97’, Journal of Peace Research, 39 (2002), 711–34; Sean Bolks and Richard Stoll, ‘Examining Conflict Escalation Within the Civilizations Context’, Conflict Management and Peace Science, 20 (2003), 85–110; Erik Gartzke and Kristian Gleditsch, ‘Identity and Conflict: Ties that Bind and Differences that Divide’, European Journal of International Relations, 12 (2006), 53–87.

⁹ Huntington, ‘The Clash of Civilizations?’, p. 48.

¹⁰ Huntington, ‘The Clash of Civilizations?’, p. 25.

¹¹ Huntington, ‘The Clash of Civilizations?’, pp. 25 and 27.

¹² Samuel P. Huntington, ‘If Not Civilizations, What?’, Foreign Affairs, 72 (1993), 186–94.

¹³ Huntington, ‘If Not Civilizations, What?’

¹⁴ Huntington, The Clash of Civilizations and the Remaking of World Order, p. 37.

¹⁵ Russett, Oneal and Cox, ‘Clash of Civilizations, or Realism and Liberalism Déjà Vu?’; Henderson and Tucker, ‘Clear and Present Strangers’; Gartzke and Gleditsch, ‘Identity and Conflict’.

¹⁶ Huntington, The Clash of Civilizations and the Remaking of World Order, p. 245.

¹⁷ Huntington, ‘The Clash of Civilizations?’, p. 39.

¹⁸ Huntington, ‘The Clash of Civilizations?’, p. 22.

¹⁹ Huntington, The Clash of Civilizations and the Remaking of World Order, p. 188.

²⁰ Samuel Huntington, ‘Religion, Culture and International Conflict after September 11’, Center Conversations, 3 (Washington, D.C.: Ethics and Public Policy Center, 2002).

²¹ No other single statement in his 1993 article attracted more criticism than this one (Huntington, The Clash of Civilizations and the Remaking of World Order, p. 258).

²² Huntington, The Clash of Civilizations and the Remaking of World Order, p. 216.

²³ Huntington, The Clash of Civilizations and the Remaking of World Order, p. 187.

²⁴ Huntington, The Clash of Civilizations and the Remaking of World Order, pp. 263ff.

²⁵ David C. Rapoport, ‘Fear and Trembling: Terrorism in Three Religious Traditions’, American Political Science Review, 78 (1984), 655–77.

²⁶ Huntington, The Clash of Civilizations and the Remaking of World Order, p. 135.

²⁷ Huntington, The Clash of Civilizations and the Remaking of World Order, p. 211.

²⁸ Huntington, The Clash of Civilizations and the Remaking of World Order, p. 217.

²⁹ Huntington, The Clash of Civilizations and the Remaking of World Order, p. 211.

³⁰ We have called them ‘terror entrepreneurs’ and ‘terror agents’ elsewhere. See Eric Neumayer and Thomas Plümper, ‘Foreign Terror on Americans’, Journal of Peace Research (forthcoming, 2010); and Thomas Plümper and Eric Neumayer, ‘The Friend of my Enemy is my Enemy: International Alliances and International Terrorism’, European Journal of Political Research (forthcoming, 2010).

³¹ This is not to say that all members of one terrorist organization have identical preferences. Rather, terrorist groups typically consist of ‘heterogeneous cells, factions, and individuals’ (Ethan Bueno de Mesquita, ‘Conciliation, Counterterrorism, and Patterns of Terrorist Violence’, International Organization, 59 (2005), 145–76, p. 146).

³² Martha Crenshaw, ‘The Causes of Terrorism’, Comparative Politics, 13 (1981), 379–99; Martha Crenshaw, ‘The Logic of Terrorism: Terrorist Behavior as a Product of Strategic Choice’, in Walter Reich, ed., Origins of Terrorism (Washington, D.C.: Woodrow Wilson Center Press, 1998), pp. 7–24; Martha Crenshaw, ‘Why America? The Globalization of Civil War’, Current History, 100 (2001), 425–32; Robert A. Pape, ‘The Strategic Logic of Suicide Terrorism’, American Political Science Review, 97 (2003), 343–61; Robert A. Pape, Dying to Win: The Strategic Logic of Suicide Terrorism (New York: Random House, 2005); Andrew H. Kydd and Barbara F. Walter, ‘The Strategies of Terrorism’, International Security, 31 (2006), 49–80.

³³ Kydd and Walter, ‘The Strategies of Terrorism’, p. 52, mention five goals: regime change, territorial change, policy change, social control and status quo maintenance. We summarize these goals under the term ‘political change’.

³⁴ David C. Rapoport, ‘The Four Waves of Modern Terrorism’, in Audrey K. Cronin and James M. Ludes, eds, Attacking Terrorism: Elements of a Grand Strategy (Washington, D.C.: Georgetown University Press, 2003), pp. 46–73; William F. Shughart II, ‘An Analytical History of Terrorism, 1945–2000’, Public Choice, 128 (2006), 7–39.

³⁵ Four, if one includes the anarchist wave dominating the period before the First World War.

³⁶ Rapoport, ‘The Four Waves of Modern Terrorism’, p. 61; similarly Ami Pedahzur, William Eubank and Leonard Weinberg, ‘The War on Terrorism and the Decline of Terrorist Group Formation: A Research Note’, Terrorism and Political Violence, 14 (2002), 141–7, at p. 146.

³⁷ Mark Sedgwick, ‘Al-Qaeda and the Nature of Religious Terrorism’, Terrorism and Political Violence, 16 (2004), 795–814.

³⁸ B. Peter Rosendorff and Todd Sandler, ‘Too Much of a Good Thing? The Proactive Response Dilemma’, Journal of Conflict Resolution, 48 (2004), 657–71.

³⁹ Kevin Siqueira and Todd Sandler, ‘Terrorists versus the Government’, Journal of Conflict Resolution, 50 (2006), 878–98.

⁴⁰ J. M. Post, ‘Terrorist Psycho-logic: Terrorist Behavior as a Product of Psychological Forces’, in Walter Reich, ed., Origins of Terrorism (Washington, D.C.: Woodrow Wilson Center Press, 1998), pp. 25–40; Jeff Victoroff, ‘The Mind of the Terrorist’, Journal of Conflict Resolution, 49 (2005), 3–42.

⁴¹ Assaf Moghadam, ‘Palestinian Suicide Terrorism in the Second Intifada: Motivations and Organizational Aspects’, Studies in Conflict & Terrorism, 26 (2003), 65–92; Anne Speckhard, ‘The Making of a Martyr: Chechen Suicide Terrorism’, Studies in Conflict & Terrorism, 29 (2006), 429–92.

⁴² This is consistent with an analysis of the propaganda from extremist Islamic movements (Manuel R.Torres, Javier Jordán and Nicola Horsburgh, ‘Analysis and Evolution of the Global Jihadist Movement Propaganda’, Terrorism and Political Violence, 18 (2006), 399–421). They find that almost all of it is in Arabic and addressed to Muslims.

⁴³ Dominic Rohner and Bruno S. Frey, ‘Blood and Ink! The Common-Interest-Game between Terrorists and the Media’, Public Choice, 133 (2007), 129–45.

⁴⁴ Rosendorff and Sandler, ‘Too Much of a Good Thing?’; Louise Richardson, What Terrorists Want (New York: Random House, 2006).

⁴⁵ Bueno de Mesquita, ‘Conciliation, Counterterrorism, and Patterns of Terrorist Violence’, p. 518.

⁴⁶ Jessica Stern, Terror in the Name of God: Why Religious Militants Kill (New York: HarperCollins, 2003); Farhad Khosrokhavar, Suicide Bombers: Allah’s New Martyrs (London: Pluto Press, 2005).

⁴⁷ Walter Enders, ‘Terrorism: An Empirical Analysis’, in Todd Sandler and Keith Hardley, eds, Handbook of Defense Economics, Volume 2 (Amsterdam: Elsevier, 2007), pp. 815–66, at p. 832.

⁴⁸ Huntington, The Clash of Civilizations and the Remaking of World Order, p. 245.

⁴⁹ Huntington, The Clash of Civilizations and the Remaking of World Order, p. 245.

⁵⁰ The military strength of the West also implies a power asymmetry that renders terror tactically opportune. This becomes nowhere clearer than in Al Qaeda’s 1996 ‘Declaration of War on America’: ‘[I]t must be obvious to you that, due to the imbalance of power between our armed forces and the enemy forces, a suitable means of fighting must be adopted … And as you know, it is wise, in the present circumstances, for the armed military forces not to be engaged in conventional fighting with the forces of the crusader enemy.’ (Al Qaeda, ‘Declaration of War Against the Americans Occupying the Land of the Two Holy Places’, in David C. Rapoport, ed., Terrorism: Critical Concepts in Political Science, Vol. IV (London and New York: Routledge, 2006), pp. 271–97, at p. 283.

⁵¹ Huntington, The Clash of Civilizations and the Remaking of World Order, p. 21.

⁵² Bernhard Lewis, ‘The Roots of Muslim Rage’; Graham E. Fuller, ‘The Future of Political Islam’, Foreign Affairs, 81 (2002), 48–60; Louise Richardson, ‘Terrorist Rivals’, Harvard International Review, 29 (2007), 66–9; Bruce Riedel, ‘Al Qaeda Strikes Back’, Foreign Affairs, 86 (2007), 24–40.

⁵³ The 2004 Strategic Survey of the International Institute for Strategic Studies came to the sobering conclusion that the American presence in Iraq ‘provided a potent global recruitment pretext for al-Qaeda, had galvanized the transnational Islamic terrorist movement and probably increased terrorist activity worldwide’ (IISS, Strategic Survey 2004 (London: International Institute for Strategic Studies, 2004), p. 169). Similarly, Pape, Dying to Win, p. 103, finds that ‘the presence of American military forces for combat operations on the homeland territory of the suicide terrorists is stronger than Islamic fundamentalism in predicting whether individuals from that country will become al-Qaeda suicide terrorists’.

⁵⁴ Edward F. Mickolus, Todd Sandler, Jean M. Murdock and Peter A. Flemming, International Terrorism: Attributes of Terrorist Events (ITERATE, Data Codebook, 2003).

⁵⁵ Mickolus, Sandler, Murdock and Flemming, International Terrorism, p. 2.

⁵⁶ Edward F. Mickolus, Todd Sandler and Jean M. Murdock, International Terrorism in the 1980s: Vol. I, 1980–1983 (Ames: Iowa State University Press, 1989), p. xii.

⁵⁷ Walter Enders and Todd Sandler, The Political Economy of Terrorism (Cambridge: Cambridge University Press, 2006), p. 372.

⁵⁸ Mickolus, Sandler, Murdock and Flemming, International Terrorism, p. 2.

⁵⁹ National Commission on Terrorist Attacks upon the United States, The 9/11 Commission Report (Washington, D.C.: 2004), p. 552.

⁶⁰ About 3 and 22 per cent of terrorist attacks involve terrorists and victims with more than one nationality, respectively.

⁶¹ http://www.sourceoecd.org/ (last accessed 6 March 2008).

⁶² http://www.sipri.org/contents/armstrad/ (last accessed 6 March 2008).

⁶³ Nils Petter Gleditsch, P. Wallensteen, M. Eriksson, M. Sollenberg and H. Strand, ‘Armed Conflict 1946–2001: A New Dataset’, Journal of Peace Research, 39 (2002), 615–37.

⁶⁴ B. A. Leeds, Alliance Treaty Obligations and Provisions (ATOP) Codebook (Houston, Tex.: Rice University, Department of Political Science, 2005); C. Sprecher and V. Krause, ‘Alliances, Armed Conflict, and Cooperation: Theoretical Approaches and Empirical Evidence’, Journal of Peace Research, 43 (2006), 363–9. We extend the 2003 value of this variable to the year 2004. Military alliances are very persistent over time, which should minimize any bias this may introduce into the estimations. The results are fully robust to constraining the estimations to the period 1969 to 2004.

⁶⁵ World Bank, World Development Indicators on CD-Rom (Washington, D.C.: World Bank, 2006).

⁶⁶ http://www.correlatesofwar.org/ (last accessed 6 March 2008); World Bank, World Development Indicators on CD-Rom.

⁶⁷ It seems impossible to us to find valid instruments, which means that we cannot use this theoretically superior alternative.

⁶⁸ Russett, Oneal and Cox, ‘Clash of Civilizations, or Realism and Liberalism Déjà Vu?’

⁶⁹ Henderson and Tucker, ‘Clear and Present Strangers’.

⁷⁰ Alberto Abadie, ‘Poverty, Political Freedom, and the Roots of Terrorism,’ American Economic Review, 96 (2006), 50–6, p. 50.

⁷¹ Alan Krueger and David Laitin, ‘Kto Kogo? A Cross-Country Study of the Origins and Targets of Terrorism’ (Working Paper, Princeton University and Stanford University, 2003); Quan Li, ‘Does Democracy Promote or Reduce Transnational Terrorist Incidents?’, Journal of Conflict Resolution, 49 (2005), 278–97.

⁷² Pape, ‘The Strategic Logic of Suicide Terrorism’; Enders and Sandler, The Political Economy of Terrorism.

⁷³ A. Colin Cameron and Pravin K. Trivedi, Microeconometrics: Methods and Applications (Cambridge: Cambridge University Press, 2005).

⁷⁴ This result seems to be at odds with the findings of Li, ‘Does Democracy Promote or Reduce Transnational Terrorist Incidents?’ Li reports that more terrorist attacks occur in countries with lower levels of political participation. One has to keep in mind, however, that his and our results are hardly comparable since we are analysing directed dyads and Li a monadic dataset.

⁷⁵ Russett, Oneal and Cox, ‘Clash of Civilizations, or Realism and Liberalism Déjà Vu?’; Henderson and Tucker, ‘Clear and Present Strangers’; Errol A. Henderson, ‘Mistaken Identity: Testing the Clash of Civilizations Thesis in Light of Democratic Peace Claims’, British Journal of Political Science, 34 (2004), 539–63.

⁷⁶ Samuel P. Huntington, ‘Try Again: A Reply to Russett, Oneal & Cox’, Journal of Peace Research, 37 (2000), 609–10, p. 609.

⁷⁷ Chiozza, ‘Is There a Clash of Civilizations?’; Bolks and Stoll, ‘Examining Conflict Escalation Within the Civilizations Context’; Gartzke and Gleditsch, ‘Identity and Conflict’.

⁷⁸ A Chow test can be problematic because it can find spurious evidence for a structural break if there is a generally upward-sloping trend in the dependent variable. Alternative tests are available from the authors on request.

⁷⁹ We let the post-Cold War period start in 1990, but results are very similar for letting it start in 1989 or 1991 instead.

⁸⁰ Note that this is true despite the fact that the full death toll of 9/11 is not included in the dependent variable, as pointed out earlier in the ‘Research Design’ section on variables.

⁸¹ Data from Russett, Oneal and Cox, ‘Clash of Civilizations, or Realism and Liberalism Déjà Vu?’

⁸² World Bank, World Development Indicators on CD-Rom.

⁸³ World Bank, World Development Indicators on CD-Rom.

⁸⁴ www.cidcm.umd.edu/polity/ (last accessed 6 March 2008).

⁸⁵ http://www.eugenesoftware.org/ (last accessed 6 March 2008).

⁸⁶ http://www.eugenesoftware.org/ (last accessed 6 March 2008).