1 For an overview of figures, see The Global Burden of Armed Violence, Geneva Declaration Secretariat, Geneva, 2008, available at www.genevadeclaration.org/pdfs/Global-Burden-of-Armed-Violence.pdf (last visited 6 March 2009).

2 The term ‘combatant deaths’ refers to soldiers killed in battle. ‘Battle deaths’ or ‘combat deaths’ refers to combatants and civilians killed during hostilities. The term ‘war deaths’ covers both battle and non-battle deaths, i.e. also people killed indirectly through war-related famine, disease, etc. See Lacina, Bethany Ann and Gleditsch, Nils Petter, ‘Monitoring trends in global combat: a new dataset of battle deaths’, European Journal of Population, Vol. 21 (2/3) (2005), pp. 145–66CrossRefGoogle Scholar, available at www.springerlink.com/content/l826g1412943w55w/ (last visited 6 March 2009). See also Edmund Cairns, A Safer Future: Reducing the Human Cost of War, Oxfam Publications, Oxford, 1997; Kalevi J. Holsti, Peace and War: Armed Conflicts and International Order, 1648–1989, Cambridge University Press, Cambridge, 1991; Herfried Münkler, Die neuen Kriege, Rowohlt, Reinbek, 2003.

3 Alastair Crooke, From Rebel Movement to Political Party: The Case of the Islamic Resistance Movement, Conflicts Forum Briefing Paper No. 3, 2007, p. 12, available at http://conflictsforum.org/briefings/Hamas-From-rebel-movement-to-political-party.pdf (last visited 6 March 2009). See also Patrick Chabal and Jean-Pascal Daloz, Africa Works: Disorder as Political Instrument, African Issues series, James Currey, Oxford, 1999.

4 Mary B. Anderson, Do No Harm: How Aid Can Support Peace or War, Lynne Rienner Publishers, Boulder/London, 1999, p. 25.

5 Direct Participation in Hostilities, Summary Report, International Committee of the Red Cross, Geneva, 31 December 2005, available at www.icrc.org/web/eng/siteeng0.nsf/html/participation-hostilities-ihl–311205 (last visited 6 March 2009).

6 Human Security Report Project, Human Security Brief 2007, Simon Fraser University, Vancouver, 2008, p. 33, available at www.humansecuritybrief.info/ (last visited 6 March 2009).

7 Mansfield, Edward D. and Pollins, Brian M., ‘The study of interdependence and conflict: recent advances, open questions and directions for future research’, Journal of Conflict Resolution, Vol. 6 (45) (2001), pp. 834–59CrossRefGoogle Scholar; Zacher, Mark W., ‘The territorial integrity norm: international boundaries and the use of force’, International Organization, Vol. 55 (2) (2001), pp. 215–50.CrossRefGoogle Scholar

8 See e.g. Bruce Russet, Grasping the Democratic Peace: Principles for a Post-Cold War World, Princeton University Press, Princeton, 1993.

9 See e.g. John Arquilla and David F. Ronfeldt (eds.), In Athena's Camp: Preparing for Conflict in the Information Age, RAND, Santa Monica, 1996; Cohen, Eliot, ‘A revolution in military affairs’, Foreign Affairs, Vol. 75 (2) (1996), pp. 37–54.CrossRefGoogle Scholar

10 See e.g. Cebrowski, Arthur K. and Garstka, John J., ‘Network-centric warfare: its origin and future’, US Naval Institute Proceedings, Vol. 124 (1) (1998)Google Scholar, available at http://all.net/books/iw/iwarstuff/www.usni.org/Proceedings/Articles98/PROcebrowski.htm (last visited 6 March 2009).

11 Corn, Geoffrey S., ‘Unarmed but how dangerous? Civilian augmentees, the law of armed conflict, and the search for a more effective test for defining permissible civilian battlefield functions’, Journal of National Security Law & Policy, Vol. 2 (2) (2008), p. 275Google Scholar, available at www.mcgeorge.edu/Documents/publications/jnslp/02_cornJCS111008%20PR.pdf (last visited 6 March 2009).

12 See e.g. Steven Metz and Douglas V. Johnson, Asymmetry and US Military Strategy: Definition, Background, and Strategic Concepts, Strategic Studies Institute, Carlisle, 2001.

13 For an excellent overview see Myriam Dunn Cavelty, Cyber-Security and Threat Politics: US Efforts to Secure the Information Age, Routledge, London, 2008, ch. 4, pp. 66–91; Edward Waltz, Information Warfare: Principles and Operations, Artech House, Boston, 1998.

14 See Dunn Cavelty, above note 13, ch. 5, pp. 91–121.

15 On the rise of private contractors see e.g. Peter W. Singer, Corporate Warriors: The Rise of the Privatized Military Industry, Cornell University Press, Ithaca, 2003; Fred Schreier and Marina Caparini, Privatising Security: Law, Practice and Governance of Private Military and Security Companies, Occasional Paper No. 6, Centre for the Democratic Control of Armed Forces, Geneva, 2005; Krahmann, Elke, ‘Security governance and the private military industry in Europe and North America’, Conflict, Security & Development, Vol. 5 (2) (2005), pp. 247–68CrossRefGoogle Scholar; Caroline Holmqvist, Private Security Companies: The Case for Regulation, SIPRI Policy Paper No. 9, Stockholm International Peace Research Institute, Stockholm, 2005.

16 We are indebted to Emmanuel Clivaz, who introduced the ‘flexibility-control balance’ concept in a recent research note as a tool for analysing the impact of private contractors on the battlefield: Emmanuel Clivaz, ‘Private contractors on the battlefield’, ISN Case Studies, International Relations and Security Network (ISN), Zurich, September 2008, available at www.isn.ethz.ch/isn/Digital-Library/Publications/Detail/?3id=93879&lng=en (last visited 6 March 2009).

17 Zarate, Juan Carlos, ‘The emergence of a new dog of war: private international security companies, international law, and the new world disorder’, Stanford Journal of International Law, Vol. 34 (1998), pp. 75–162Google Scholar; Gaul, Matt, ‘Regulating the new privateers: private military service contracting and the modern marquee and reprisal clause’, Loyola of Los Angeles Law Review, Vol. 31 (1998), pp. 1489–522Google Scholar; Kinsey, Christopher, ‘Challenging international law: a dilemma of private security companies’, Conflict, Security and Development, Vol. 5 (3) (2005), pp. 269–93.CrossRefGoogle Scholar

18 Singer, above note 15.

19 For standard definitions and data sets, see the home page of the Uppsala Conflict Data Program, available at www.pcr.uu.se/research/UCDP/index.htm (last visited 6 March 2009). For an introduction see Kalyvas, Stathis N., ‘The ontology of “political violence”: action and identity in civil wars’, Perspectives on Politics, Vol. 1 (3) (2003), pp. 475–94.CrossRefGoogle Scholar

20 Lacina and Gleditsch, above note 2.

21 BBC World News, ‘Rwanda: how the genocide happened’, available at http://news.bbc.co.uk/2/hi/africa/1288230.stm (last visited 6 March 2009); Gérard Prunier, The Rwanda Crisis: History of a Genocide, Columbia University Press, New York, 1997.

22 See e.g. Kristian Skrede Gleditsch, All International Politics is Local: The Diffusion of Conflict, Integration, and Democratization, University of Michigan Press, Ann Arbor, 2002.

23 See e.g. Humphreys, Macartan and Weinstein, Jeremy M., ‘Who fights? The determinants of participation in civil war’, American Journal of Political Science, Vol. 52 (2) (2008), pp. 436–55.CrossRefGoogle Scholar

24 See e.g. Collier, Paul and Hoeffler, Anke, ‘Greed and grievance in civil wars’, Oxford Economic Papers, Vol. 56 (4) (2004), pp. 563–95CrossRefGoogle Scholar; Fearon, James D. and Laitin, David D., ‘Ethnicity, insurgency, and civil war’, American Political Science Review, Vol. 97 (1) (2003), pp. 75–90.CrossRefGoogle Scholar

25 Paul Collier, Economic Causes of Civil Conflict and Their Implications for Policy, Department of Economics, Oxford University, 2006, available at http://users.ox.ac.uk/~econpco/research/pdfs/EconomicCausesofCivilConflict-ImplicationsforPolicy.pdf (last visited 6 March 2009).

26 For a succinct criticism of Collier and Hoeffler's approach see Laurie Nathan, The Frightful Inadequacy of Most of the Statistics: A Critique of Collier and Hoeffler on Causes of Civil War, Crisis States Discussion Paper, LSE, 2005, available at www.research4development.info/PDF/Outputs/CrisisStates/dp11.pdf (last visited 6 March 2009).

27 Paul Richards, Fighting for the Rain Forest: War, Youth and Resources in Sierra Leone, Heinemann, Oxford, 1996; Azam, Jean-Paul, ‘On thugs and heroes: why warlords victimize their own civilians’, Economics of Governance, Vol. 7 (1) (2006), pp. 53–73CrossRefGoogle Scholar; Roger D. Petersen, Resistance and Rebellion: Lessons from Eastern Europe, Cambridge University Press, Cambridge, 2001.

28 See e.g. Stathis N. Kalyvas, The Logic of Violence in Civil War, Cambridge University Press, Cambridge, 2006.

29 See e.g. Collier and Hoeffler, above note 24. We are indebted to Johannes Hamacher for help with the review of literature on the relationship between civilians and warlords.

30 See e.g. Charles Tilly, Coercion, Capital and European States: AD 990–1992, Blackwell, Cambridge, 1990; Virginia M. Bouvier, ‘Colombia's crossroads: the FARC and the future of the hostages’, USI Peace Briefing, June 2008; ‘War and drugs in Colombia’, Latin American Report 11, International Crisis Group (ICG), 27 January 2005, available at www.crisisgroup.org/home/index.cfm?id=3238&l=1 (last visited 6 March 2009).

31 See e.g. Jeremy M. Weinstein, Inside Rebellion: The Politics of Insurgent Violence, Cambridge University Press, Cambridge, 2007.

32 See e.g. Zahar, Marie-Joëlle, ‘Protégés, clients, cannon fodder: civilians in the calculus of militias’, International Peacekeeping, Vol. 7 (4) (2000), pp. 107–28CrossRefGoogle Scholar; MacKinlay, John, ‘Defining warlords’, International Peacekeeping, Vol. 7 (1) (2000), pp. 48–62.CrossRefGoogle Scholar

33 Chabal and Daloz, above note 3.

34 See e.g. Salehyan, Idean and Gleditsch, Kristian Skrede, ‘Refugees and the spread of civil war’, International Organization, Vol. 60 (2) (2006), pp. 335–66CrossRefGoogle Scholar; Sarah Lischer, Dangerous Sanctuaries: Refugee Camps, Civil War, and the Dilemmas of Humanitarian Aid, Cornell University Press, Ithaca, N.Y., 2005.

35 See e.g. Verwimp, Philip, ‘Machetes and firearms: the organization of massacres in Rwanda’, Journal of Peace Research, Vol. 43 (5) (2006), pp. 5–22.CrossRefGoogle Scholar

36 Annika Åberg, Sabina Laederach, David Lanz, Jonathan Litscher, Simon J. A. Mason and Damiano Sguaitamatti, ‘Unpacking the mystery of mediation in African peace processes’, report, Mediation Support Project, Center for Security Studies (CSS) and swisspeace, Zurich/Berne, October 2008, available at www.css.ethz.ch/Mediation_in_Africa_full.pdf (last visited 6 March 2009); Simon Mason, ‘Learning from the Swiss mediation and facilitation experiences in Sudan’, working paper, Mediation Support Project, Center for Security Studies (CSS) and swisspeace, Zurich/Berne, May 2007, available at www.swisspeace.ch/typo3/fileadmin/user_upload/pdf/Mason-Learning_from_Swiss_mediation_experiences_in_Sudan_May_2007.pdf (last visited 6 March 2009). See also Chester A. Crocker, Fen O. Hampson and Pamela Aall, Taming Intractable Conflicts: Mediation in the Hardest Cases, USIP Press Books, Washington, 2004.

37 See e.g. Christoph Coker, Globalization and Insecurity in the Twenty-First Century: NATO and the Management of Risk, Adelphi Paper 345, International Institute of Security Studies, London, 2002; Richard L. Kugler and Ellen L. Frost, The Global Century: Globalization and National Security, National Defense University Press, Fort Lesley J. McNair, Washington, 2001, available at www.ndu.edu/inss/books/Books_2001/Global%20Century%20-%20June%202001/globcencont.html (last visited 6 March 2009); Cha, Victor D., ‘Globalization and the study of international security’, Journal of Peace Research, Vol. 37 (3) (2000), pp. 391–403.CrossRefGoogle Scholar

38 See e.g. Fawaz A. Gerges, The Far Enemy: Why Jihad Went Global, Cambridge University Press, Cambridge, 2005; Keohane, Robert, ‘The globalization of informal violence, theories of world politics, and the “liberalism of fear”’, Dialogue–IO, Vol. 1 (2002), pp. 29–43.CrossRefGoogle Scholar

39 See e.g. Friesendorf, Cornelius, ‘Squeezing the balloon? United States air interdiction and the restructuring of the South American drug industry in the 1990s’, Crime, Law and Social Change, Vol. 44 (1) (2005), pp. 35–78.CrossRefGoogle Scholar

40 See e.g. Ivan Arreguin-Toft, How the Weak Win Wars: A Theory of Asymmetric Conflict, Cambridge University Press, Cambridge, 2005; Martin van Creveld, The Transformation of War, Free Press, New York, 1991.

41 See e.g. Doron Zimmermann and Andreas Wenger (eds.), How States Fight Terrorism: Policy Dynamics in the West, Lynne Rienner, Boulder, 2007.

42 See e.g. Samuel P. Huntington, The Clash of Civilizations and the Remaking of World Order, Simon & Schuster, New York, 1996.

43 See e.g. Bruce Hoffmann, Inside Terrorism, Columbia University Press, New York, 1998, pp. 197–228.

44 See e.g. Cavelty, Myriam Dunn, ‘Information operations: Trends and controversies’, CSS Analyses in Security Policy, Vol. 34 (3) (2008)Google Scholar, Center for Security Studies, ETH Zurich, available at www.crn.ethz.ch/publications/crn_team/detail.cfm/id=57145 (last visited 6 March 2009).

45 We are indebted to Maurice Voyame for his helpful input on which this paragraph is based. See also Maurice Voyame, ‘The notion of “direct participation in hostilities” and its implications on the use of private contractors under international humanitarian law’, in Thomas Jäger and Gerhard Kümmel (eds.), Private Military and Security Companies: Changes, Problems, Pitfalls and Prospects, VS Verlag für Sozialwissenschaften, Wiesbaden, 2007, pp. 361–76.

46 Hoffmann, above note 43, pp. 1–42.

47 See e.g. David C. Gompert, John Gordon, IV, Adam Grissom, David R. Frelinger, Seth G. Jones, Martin C. Libicki, Edward O'Connell, Brooke K. Stearns and Robert E. Hunter, War by Other Means: Building Complete and Balanced Capabilities for Counterinsurgency, RAND, Santa Monica, 2008, available at www.rand.org/pubs/monographs/MG595.2/ (last visited 6 March 2009).

48 See e.g. Clivaz, above note 16; Dina Rasor and Robert Baumann, Betraying Our Troops: The Destructive Results of Privatizing War, Palgrave, New York, 2007.