International Relations Private Military and Security Companies (PMSCs)
Birthe Anders
  • LAST REVIEWED: 24 May 2017
  • LAST MODIFIED: 24 May 2017
  • DOI: 10.1093/obo/9780199743292-0209


Private force in warfare is nothing new. Italian Condottieri during the Renaissance wars and Hessian Landsknechte during the American War of Independence are well-known examples of arms in the hands of groups of private individuals, not soldiers. Individual mercenaries, which of course still exist, move from one employer to the next, shifting allegiance to who currently pays them. To this day, the mercenary image heavily influences views about a new form of private and often armed actor in warfare: Private Military and Security Companies (PMSCs). Over the course of the past twenty-five years, PMSCs have developed to be an important actor in war and conflict zones around the globe. They are private companies who trade in security and/or military services, mostly outside their home states. Among the services offered are armed and unarmed guarding of personnel and assets, intelligence, military support and logistics services, and security training. Most companies draw on a labor pool largely compiled of former soldiers and law enforcement officers. In contrast to the example named above, PMSCs are permanent endeavors with a corporate structure. When the first companies came to public attention in the early 1990s, some of them offered combat services—a fact that influences not only public perception of the companies to this day, but also sparked some of the first academic inquiries into the subject, such as Shearer’s Adelphi Paper monograph (Shearer 1998, cited under Edited Volumes, Handbooks, and Overviews) and Coker’s article “Outsourcing War” (Coker 1999). Many of the early publications tried to grasp “the industry” as a whole, developed typologies of company types, distinguishing between Private Military and Private Security Companies—a distinction that is widely regarded as impractical these days, as many companies offer both types of services. When the industry grew and diversified in the late 1990s, so did PMSC research. Key strands of research concern the relation between PMSCs and the state, law and regulation, contracting in Iraq and Afghanistan, and more recently also the role of the individual in the market for security as well as non-state contracting. Until now, no single journal has crystallized as the key address for PMSC research, but publications are found across security studies journals: Journal of Strategic Studies, Security Studies, Armed Forces and Society, Contemporary Security Policy, Security Dialogue, International Security, International Peacekeeping, and others. The field of PMSC research can be understood as a subfield of security studies and draws on a variety of disciplines, in particular law, ethics, political science, history, and sociology. PMSCs are an important subject of study as they raise many questions for contemporary international relations: about the legitimate use of force, about the state’s role in war and peace, about change and continuity in the practice of warfare as well as about the role of non-state actors.

Monographs: PMSCs, the State, and the Marketplace for Security Services

Many of the services PMSCs offer have long been the exclusive domain of states. If and how their existence and growth affects relations between the state, its citizens and its soldiers is thus an important question in PMSC research. Early publications, mostly monographs, focus on why the industry developed and how it can be classified, described, and understood. Cilliers and Mason 1999 examines some of the first PMSCs in Sierra Leone, Angola, and other African countries in the 1990s in light of weak state security structures. An influential typology was put forward by Singer 2008. In his tip-of-the-spear typology, he differentiates four types of companies, based on their distance to the battlefield. Avant 2005 moved on to conceptual questions of what PMSC contracting means for the state and its control over legitimate force, while Krahmann 2010 explains diverging contracting approaches in Western countries by different understandings of the state and the citizen soldier. Overall, the United States and United Kingdom prevail as focus of analyses. Not only are many companies headquartered there, both governments contract PMSCs, with the United States remaining the uncontested leader when it comes to contract volume. This leads Dickinson 2011 to ask whether PMSC use affects core public values in the United States, such as public participation and transparency regarding how tax money is spent. Dunigan 2011 discusses problems emanating from different types of contracting such as PMSCs deployed alongside or instead of the US military. Abrahamsen and Williams 2011 depart from the focus on Western case studies and although their book is about private security in the broadest sense, not just PMSCs, provide useful insights into security governance in four African countries.

  • Abrahamsen, Rita, and Michael C. Williams. Security Beyond the State: Private Security in International Politics. Cambridge, UK: Cambridge University Press, 2011.

    Discusses PMSCs in the broader context of what is termed “security assemblages,” meaning the de-territorialized provision and governance of security. Draws on case studies from four African countries, including from private security in the oil and diamond industries.

  • Avant, Deborah D. The Market for Force: The Consequences of Privatizing Security. Cambridge, UK: Cambridge University Press, 2005.

    DOI: 10.1017/CBO9780511490866

    Remains a standard-setting work in PMSC research—a theoretically grounded examination of state control of force and how the use of PMSCs affects the functional, political, and social dimensions of control. Draws on examples for state contracting from Sierra Leone, Croatia, as well as the United States and regulation cases in the United States, South Africa, and the United Kingdom.

  • Bruneau, Thomas C. Patriots for Profit. Contractors and the Military in U.S. National Security. Stanford, CA: Stanford University Press, 2012.

    Looks at the role of contractors in US civil-military relations, particularly related to the effectiveness and efficiency of contractors.

  • Cilliers, Jakkie, and Peggy Mason, eds. Peace, Profit or Plunder? The Privatisation of Security in War-Torn African Societies. Pretoria, South Africa: Institute for Security Studies, 1999.

    Examines various cases of weak state structures and how this led to the use of private military and security services in several African countries in the 1990s, including Sierra Leone and Angola.

  • Dickinson, Laura A. Outsourcing War and Peace: Preserving Public Values in a World of Privatized Foreign Affairs. New Haven, CT: Yale University Press, 2011.

    Argues that outsourcing security services to PMSCs affects core public values in the United States, including human rights, limits on the use of force, transparency, and public participation. As a reversal of US contracting is unlikely, current regulation should be improved, including better use of contracts.

  • Dunigan, Molly. Victory for Hire: Private Security Companies’ Impact on Military Effectiveness. Stanford, CA: Stanford University Press, 2011.

    Asks how the United States’ use of PMSCs affects the country’s military effectiveness. Different operational scenarios are discussed, such as PMSCs deployed alongside and in lieu of the US military, with suggestions of how to remedy problems from the different setups.

  • Krahmann, Elke. States, Citizens and the Privatisation of Security. Cambridge, UK: Cambridge University Press, 2010.

    DOI: 10.1017/CBO9781139042727

    Examines state contracting from PMSCs in the United Kingdom, the United States, and Germany through the lens of republican and liberal models of democracy. Drawing on the role of the state, the military, and society within these competing models the book convincingly explains the approach to outsourcing each of these countries has taken.

  • Leander, Anna. “The Market for Force and Public Security: The Destabilizing Consequences of Private Military Companies.” Journal of Peace Research 42.5 (2005): 605–622.

    Argues that the use of PMSCs undermines the consolidation of public security in the weakest African states. While single cases might speak to the contrary, a comparative analysis of market dynamics in several countries leads to the conclusion that the market for force becomes a self-perpetuating cycle. One of several works by the author which are critical as to PMSCs’ effect on the state monopoly of legitimate force.

  • McFate, Sean. The Modern Mercenary. Private Armies and What They Mean for World Order. Oxford: Oxford University Press, 2015.

    With cases studies on Liberia and Somalia as well as personal recollections from the author’s time as a contractor, the emergence and current scope of the PMSC industry is analyzed. The author argues that we are seeing a “neomedivalism” in contemporary international relations, particularly relating to the proliferation of private force.

  • Singer, Peter W. Corporate Warriors: The Rise of the Privatized Military Industry. Ithaca, NY: Cornell University Press, 2008.

    Now a classic of PMSC research, in which Singer coined his much discussed “tip-of-the-spear” typology which categorizes companies according to their distance to the battlefield. With case studies including Military Professional Resources Inc. (MPRI) in the Croatia and other parts of the Balkan region and Executive Outcomes in Sierra Leone. Updated edition, contains a postscript “The Lessons of Iraq.”

  • Thomson, Janice E. Mercenaries, Pirates, and Sovereigns. Princeton, NJ: Princeton University Press, 1994.

    A useful examination of the relationship between private forces and the state in history, with a particular focus on pirates, mercenaries, and mercantile companies as well as reasons for why non-state violence was delegitimized.

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