DON'T LOSE ACCESS:
Your IP access to ForeignPolicy.com will expire on June 15.
To ensure uninterrupted reading, please contact Rachel Mines, sales director, at firstname.lastname@example.org.
Why mercenaries are a fact of warfare.
For nearly three centuries, the accepted international norm has been that only nation — states should be permitted to fight wars. Not surprisingly, the rise of private military companies in the 1990s — and the possibility that they may view conflict as a legitimate business activity — has provoked outrage and prompted calls for them to be outlawed. The popular press has labeled these companies "mercenaries" and "dogs of war," conjuring up images of freebooting and rampaging Rambos overthrowing weak — usually African — governments. At a press conference convened in June 1997 to discuss the ongoing civil war in Sierra Leone, Secretary General Kofi Annan bristled at the suggestion that the United Nations would ever consider working with "respectable" mercenary organizations, arguing that there is no "distinction between respectable mercenaries and non-respectable mercenaries."
But is this depiction fair? Certainly these soldiers might meet the three most widely accepted criteria defining a mercenary: They are foreign to a conflict; they are motivated chiefly by financial gain; and, in some cases, they have participated directly in combat. They differ significantly, however, from infamous characters such as Irishman "Mad" Mike Hoare and Frenchman Bob Denard, who fought in the Congo and elsewhere in the 1960s. What most sets today’s military companies apart is their approach. They have a distinct corporate character, have openly defended their usefulness and professionalism, have used internationally accepted legal and financial instruments to secure their deals, and so far have supported only recognized governments and avoided regimes unpalatable to the international community. As Enrique Bernales Ballesteros, the U.N.’s special rapporteur on the use of mercenaries, has noted, personnel working for these companies, "even when they have a military background and are highly paid" cannot be considered as "coming with, in the legal scope of mercenary status."
Dismissing private’ sector military personnel as little more than modern-day soldiers of fortune would not only be simplistic but would obscure the broader issues that these military companies raise. Why have they emerged in the 1990s? What role might they play in the future? Can they be regulated? Practitioners and academics who specialize in conflict resolution typically argue that private military companies hinder efforts to end wars and broker peace. Yet, the evidence suggests that coercion is often essential to breaking deadlocks and bringing opposing parties to the negotiating table. In this context, military companies can be seen not as part of the problem but as part of the solution — especially for struggling but legitimate governments that lack the resources to field effective fighting forces. As the political and economic costs of peacekeeping continue to escalate, it may increasingly make sense for multilateral organizations and Western governments to consider outsourcing some aspects of these interventions to the private sector.
These Guns For Hire
Private military forces are as old as warfare itself. The ancient Chinese, Greek, and Roman armies employed large numbers of mercenaries, and mercenaries comprised about half of William the Conqueror’s army in the eleventh century. During the fourteenth century, Italian city-states contracted private military forces, known as condottieri, to protect themselves — an early acknowledgment that hiring mercenaries can often prove more cost-effective than maintaining standing armies. Private forces have also served states’ immediate strategic interests. The United Kingdom, for example, hired 30,000 Hessian soldiers to fight in the American War of Independence to avoid conscripting its own citizens. In the late eighteenth century, foreigners comprised half of the armed forces of Prussia and a third of the armies of France and the United Kingdom. Mercantile companies were licensed by the state to wage war to serve their countries’ economic interests. In 1815, the East India Company, which colonized India on behalf of the British government, boasted an army of 150,000 soldiers.
But with the rise of nationalism in the nineteenth century, the idea of fighting for one’s country rather than for commercial interests gained currency. Governments came to command a monopoly over violence and became increasingly keen on limiting the risks to their neutrality that arose when their citizens fought other peoples’ wars. Conscripted armies under the control of the state became the norm-apart from the activities of a few individuals that capitalized on the upheavals caused by African independence throughout the 1960s and 1970s.
In the past decade, however, the increasing inability of weak governments to counter internal violence has created a ready market for private military forces. This demand has also been fueled by a shift in Western priorities. The strategic interests of major powers in countries such as Mozambique, Rwanda, and Sierra Leone have declined with the end of the Cold War. As a result, Western countries are more reluctant to intervene militarily in weak states, and their politicians are disinclined to explain casualties to their electorates. Furthermore, Western armies, designed primarily to fight the sophisticated international conflicts envisaged by Cold War strategists, are ill equipped to tackle low-intensity civil wars, with their complicated ethnic agendas, blurred boundaries between combatants and civilians, and loose military hierarchies. The failed U.S.-led involvement in Somalia in 1993 reinforced American resolve never to enter a conflict unless vital domestic interests were at stake.
Meanwhile, U.N. peacekeeping efforts have fallen victim to Western governments’ fears of sustaining casualties, becoming entangled in expanding conflicts, and incurring escalating costs. The number of personnel in U.N. operations has fallen from a peak of 76,000 in 1994 to around 15,000 today. Multilateral interventions appear increasingly likely to be limited to situations where the U.N. gains the consent of the warring parties rather than — as allowed under Chapter VII of the U.N. Charter — to be designed to enforce a peace on reluctant belligerents. Bilateral, as well as multilateral, commitments have also been trimmed. France’s long-standing deployment of troops in its former African colonies, for example, has declined: French troops will be cut by 40 percent to about 5,000 by 2000. Paris has stated that it will no longer engage in unilateral military interventions in Africa, effectively creating a strategic vacuum.
Into this gap have stepped today’s private military companies. Most such enterprises hail from South Africa, the United Kingdom, the United States, and occasionally France and Israel. They all share essentially the same goals: to improve their client’s military capability, thereby allowing that client to function better in war or deter conflict more effectively. This process might involve military assessments, training, or occasionally weapons procurement. Direct involvement in combat is less common, although two companies, Executive Outcomes (EO) of South Africa and Sandline International of Great Britain, advertise their skills in this area. EO has provided training and strategic advice to the armed forces of Angola and Sierra Leone; its apartheid-era soldiers have fought in both countries.
Other companies, such as Military Professional Resources Incorporated (MPRI), a Virginia-based firm headed by retired U.S. army generals, has limited its services to training and has hired former U.S. military personnel to develop the military forces of Bosnia-Herzegovina and Croatia. Some organizations engage in more passive activities, such as protecting premises and people. The British company Defence Systems Limited, for example, guards embassies and protects the interests of corporations working in unstable areas. Other outfits provide businesses with risk analyzes, and several have developed specialist expertise in resolving the kidnapping incidents that plague firms operating in Latin America.
Military companies are unfettered by political constraints. They view conflict as a business opportunity and have taken advantage of the pervasive influence of economic liberalism in the late twentieth century. They have also been quick to adapt to the complex agendas of civil wars. Their ability to operate has been enhanced by an expanded pool of military expertise made available by reductions in Western forces. Many recruits come from highly disciplined military units, such as the British Special Air Service and the South African and American special forces. Likewise, cheap and accessible Soviet-made weaponry has helped strengthen the companies’ capabilities.
When help from other quarters was unavailable, Sir Julius Chan, prime minister of Papua New Guinea, claimed in 1997 that he was forced to "go to the private sector" to counter Bougainville Revolutionary Army (BRA) insurgents. After negotiations with the BRA collapsed, Chan signed a $36 million contract with Sandline International to train his national forces and plan an offensive against the separatists. The government was particularly anxious to reopen Bougainville’s Panguna Copper Mine, once the source of 30 percent of the country’s export earnings.
Western mining corporations also stand to benefit when a private military company restores order, thereby raising questions as to whether these business entities share any formal ties. In April 1997, the London Independent reported that Anthony Buckingham, a director of Heritage Oil and Gas and Branch Energy, introduced EO to the governments of Angola and Sierra Leone. But Buckingham has emphatically stated that "there is no corporate link between Executive Outcomes and the Branch Heritage group." EO officials likewise strongly deny any financial or operational/business links with mining companies. While critics decry even this nebulous relationship as neocolonialist behavior in the worst tradition of Cecil Rhodes, Buckingham observes that "If there is no stability there is no investment and no one benefits."
The lure of rich resources and the risks of exploiting them in unstable areas are powerful incentives for companies to maintain stability in weak states. This motivation can also chime with a government’s own wishes. A mining company depends on security to protect its investments; a beleaguered government buys increased security to shore up its rule, while the prospect of mining revenues can supplement its coffers. Furthermore, a military company, while strengthening its client government’s military performance, protects a mining company’s operations because revenues from these sources guarantee its payment. In the developing world, minerals and hardwoods may soon emerge as the currency of stability. The source of payment is a crucial difference between the intervention of a military company and that of the U.N., which is funded by donors, not by the state in question. Coupling multinational companies with an external security force potentially gives foreigners powerful leverage over a government and its affairs — a risk that some governments appear willing to take.
Another trend, reminiscent of the privateers of earlier centuries, is the willingness of private military companies to act as proxies for the Western governments. MPRI has specialized exclusively in military services, originally for the privatization-minded U.S. Department of Defense. MPRI’S first two major international contracts were with the Croatian government in 1994 to update its Warsaw Pact-oriented military. When the sophisticated Croatian offensive, Operation Storm, took the Serb-held Krajina enclave in August 1995, there was inevitable suspicion that MPRI was involved. The operation played an important role in reversing the tide of war against the Serbs and in bringing both sides to the negotiating table. MPRI, although denying that it had played a role, has benefited from these rumors. In 1995, the company was contracted, in the aftermath of the Dayton accord, to strengthen the Muslim-Croat Federation’s army in order to deter Bosnian Serb aggression. Since it is funded by the contracting government, MPRI has delivered a cheaper service and done so at less political risk than would have been possible had U.S. troops been used. The scenario serves as an example of how the private military sector can allow policymakers to achieve their foreign policy goals free from the need to secure public approval and safe in the knowledge that should the situation deteriorate, official participation can be fudged. Other American companies have also worked to further administration policy. Corporate giants such as Science Applications International Corporation and Braddock, DU.N.n & McDonald, Inc. and its subsidiary Vinnell Corporation are primarily high-technology suppliers to the military-industrial market but have also diversified into military training. They are contracted by the Saudi government to upgrade and train its armed forces in the use of mainly U.S. weaponry. Some British companies have also supported government interests: The London-based Saladin Security, for example, trains Omani government forces working alongside British Army officers who are seconded there. But on the whole, British companies are smaller and less diversified than their U.S. counterparts and have tended to focus on protecting commercial interests. Nonetheless, they maintain close contacts with Britain’s Ministry of Defense and are an important source of intelligence.
Portrait of a Private Army
In its promotional literature, Executive Outcomes (EO) describes itself as a company with a "solid history of success," thanks to the efforts of its "highly effective work force." This work force is essentially a demobilized army for hire. Based in South Africa, the company was established in 1989 by Eeben Barlow and is staffed almost exclusively by veterans from the former South African Defense Force. EO claims to be able to draw on over 2,000 personnel and forces, all of whom are assembled on a contract-by-contract basis and recruited chiefly by word-of-mouth. This policy has not only ensured quality control but a preexisting military hierarchy of highly experienced troops. EO personnel have distinguished themselves from other companies by entering into combat, claiming that accompanying the clients’ troops increases their effectiveness and confidence.
EO’s first major contract was in Angola in May 1993 to rescue the Soyo oil fields in the north from the rebel National Union for the Total Independence of Angola (U.N.ITA). The Angolan government then hired over 500 personnel from September 1993 to January 1996 for an estimated $40 million a year (including weaponry) to train nearly 5,000 soldiers. EO’s arrival, coinciding with the lifting of the arms embargo on Angola, helped reverse the course of the war, and UNITA suffered significant defeats. EO’s second contract, this time with the Sierra Leonean government in May 1995, lasted 22 months and cost $35 million — about one-third of the country’s defense budget. EO, working with local civilian militias, battered the Revolutionary United Front into submission. In February 1997, EO was subcontracted to the British military company, Sandline International, to train and plan military operations against the Bougainville Resistance Army in Papua New Guinea.
EO’s military effectiveness testifies to its expertise in low-intensity conflict. It has planned its operations closely with government officials and uses government equipment, although it has arranged the purchase of weaponry. Its hallmark has been its highly mobile operations using MI-17 helicopter troop carriers, on occasion supported by MI-24 helicopter gunships and Soviet-made ground attack aircraft. But EO’s biggest strength has been its use of intelligence capabilities, particularly through the cultivation of local populations, augmented with night-sighting and radio intercept devices. Casualties have remained relatively light: EO acknowledges that 11 of its personnel died in Angola, with seven still missing, and four killed in Sierra Leone. Two others died from accident and sickness.
The Future of Peacekeeping?
Some private military companies, such as EO, possess sufficient coercive capability to break a stalemate in a conflict. Unlike multinational forces, they do not act impartially but are hired to win a conflict (or deter it) on the client’s terms. EO and Sandline International have argued that military force has an under-utilized potential to bring conflicts to a close. However, bludgeoning the other side into accepting a peace agreement runs in diametric opposition to most academic studies of conflict resolution. These studies center on consent: bringing warring sides together with the implicit assumption that each wants to negotiate an end to the war. To a large degree, the international community has responded to civil wars in this manner, especially those of limited strategic interest. Ceasefires act as holding positions; mediation seeks to bring combatants to an agreement. Peacekeepers, acting under mandates to be evenhanded and to use minimal force, are deployed to support this process.
The flaw in this approach is that according to recent empirical studies, outright victories, rather than negotiated peace settlements, have ended the greater part of the twentieth century’s internal conflicts. Combatants in Angola, Bosnia, and Sierra Leone consistently resisted a negotiated, consent-based settlement. There appeared to be little chance of a breakthrough until more coercive measures were applied. So why has the international community continued to persist with negotiated settlements and even-handedness in cases where one side was clearly at fault? The reason, for the most part, is self-interest. Such an approach avoids direct intervention and the subsequent political risks.
Yet when it suits them, Western states have also been proponents of "battlefield diplomacy" to resolve conflicts. This approach was favored throughout the Cold War when the object was to limit Soviet expansionism. More recently, the United States tacitly supported the aims of Laurent Kabila’s military campaign to oust president Mobutu Sese Seku in the former Zaire. France allegedly backed former military ruler Denis Sassou Nguesso’s overthrow of Congolese president Pascal Lissouba in September 1997. And by condoning the Croatian capture of Serb-held Krajina, Washington was implicitly recognizing the value of resolution through force.
However, the likelihood that a military solution can bring durable peace to a country depends on the nature of the peace agreement, as well as on how effectively follow up measures such as demobilization, cantonment of fighters, and rehabilitation are implemented. Despite EO’s involvement in Angola, for example, peace is still not finally secure. Nevertheless, its military involvement was instrumental in turning the tables of war in favor of the government’s side, a development that coerced the National Union for the Total Independence of Angola (U.N.ITA) to negotiate and eventually sign the 1994 Lusaka Accords. Similarly, in Sierra Leone, EO battered the Revolutionary United Front (RUF) faction into submission, creating sufficient stability to hold the first elections in 27 years. Later military offensives compelled the RUF to return to the negotiating table and sign a peace accord in November 1997. But just three months after EO left, the government was overthrown by disgruntled members of the armed forces, highlighting the importance of implementing post-conflict measures.
These shortcomings are often seized upon as proof that the efforts of military companies have failed. But EO has always acknowledged its limitations. The U.N. did not engage members of EO in Sierra Leone, possibly because it chose to label them as mercenaries and therefore as untouchable. The entire episode illustrates that it is better to acknowledge the existence of military companies and engage them politically than to ignore them and hope that somehow a peace agreement will stay intact.
Regulating the Market
Since the demand for military force is unlikely to end anytime soon, military companies, in their various guises, appear here to stay. Should there be some attempt to regulate them, or is it the right of sovereign states — as with the purchase of weaponry — to employ who they wish as long as they ensure that their employees behave within acceptable bounds? There is widespread discomfort with a laissez-faire approach, most of it caused by military companies’ lack of accountability. Although most military companies have only worked for legitimate governments, there is little to stop them from working for rebel movements in the future.
To make matters even more complicated, deciding which is the "legitimate" side in a civil conflict is not always straightforward. Many modern governments were once classified as "insurgents" or "terrorists" while in opposition, among them South Africa’s African National Congress and Ugandan President Yoweri Museveni’s National Resistance Army. The governments that grew out of these movements are now internationally recognized.
Military companies are motivated first and foremost by profit and are responsible primarily to their shareholders. Consequently, financial losses, in spite of any strategic or political considerations, may prompt a company to pull out. There are also few checks on their adherence to human-rights conventions. The problem is not a lack of human-rights law. During times of war, the employees of military companies fall under the auspices of Common Article 3 of the Geneva Conventions, which is binding on all combatants. They are also bound by a state’s obligations to U.N. human-rights conventions as "agents" of the government that employs them. What is absent is adequate independent observation of their activities — a feature common to all parties in a conflict but especially characteristic of military companies that have no permanent attachments to national governments.
Efforts at controlling mercenaries through international law in the 1960s and 1970s were led by African states that faced a skeptical reception from the United States and major European powers. The most accepted definition of a mercenary, found in Article 47 of the 1977 Additional Protocols to the Geneva Conventions, is so riddled with loopholes that few international-law scholars believe it could withstand the rigors of the courtroom. International apathy is palpable. France and the United States have not signed the Additional Protocols, and the U.N.’s 1989 International Convention against the Recruitment, Use, Financing, and Training of Mercenaries has attracted only 12 signatories. Three of these signatories, Angola, the former Yugoslavia, and the former Zaire, have gone on to employ mercenaries. Most states have domestic laws that ban mercenaries but few, if any, have acted on them. Britain’s Foreign Enlistment Act, for example, was introduced in 1870, and there has yet to be a prosecution.
The drive to regulate military companies has been most passionate when home governments — not those who contract them — are affected. The British government is currently investigating regulation after Sandline International, claiming it had clearance from the Foreign and Commonwealth Office, appeared to violate U.N. sanctions by supplying arms and military expertise to the ousted Sierra Leonean government. Sandline executives, portrayed in the media as "mercenaries," embarrassed Britain’s new Labour Party government, which had entered office touting its platform of an "ethical" foreign policy.
South Africa too has come under both domestic and international pressure to control the increasing number of companies based there. Its parliament passed the Regulation of Foreign Military Assistance Bill in May 1998. Privately, however, most commentators in South Africa believe that while the legislation provides a framework for government policy and satisfies its critics, its real impact will be limited. Military companies are mostly registered offshore and can easily relocate to other countries, making it difficult to pin them down under specific jurisdictions. A growing trend is for international companies to form joint ventures with local companies, avoiding the effects of the legislation in anyone country. Angola, for example, has over 80 security firms, many of them in joint ownership. Companies can also easily disguise their activities by purporting to be security companies performing protection services while actually engaging in more coercive military operations.
The principal obstacle to regulating private military companies has been the tendency to brand them as "mercenaries" of the kind witnessed in Africa 30 years ago, rather than to recognize them as multinational entrepreneurs eager to solidify their legitimacy. Consequently, regulation can be best achieved through constructive engagement. This process would likely expose governments and international institutions to accusations of sanctioning the use of "soldiers of fortune" to shore up the international system. Yet, this tack offers the international community greater leverage to influence the activities of companies that believe legitimacy is the key to their future growth and prosperity. In an effort to broaden their appeal, for instance, military companies have offered greater transparency. Sandline International maintains that it is prepared to place itself under the scrutiny of international monitors and accept an international regulatory framework. This pledge is a necessary step; a careful audit would establish corporate links that might affect the company’s operations.
Engagement could well begin with dialogue between key multilateral institutions and the private military sector. Liaison at senior levels of the U.N., for example, is needed, and the Department of Peacekeeping is an obvious starting point. U.N. field personnel should be permitted to contact military companies and plan strategies for conflict resolution where appropriate. Had there been a structured transition between EO’s departure and the planned deployment of U.N. observers, the military coup in Sierra Leone might have been averted. EO could have maintained a threat of enforcement that would have bought time for the U.N. to fully implement post-conflict programs, allowing RUF combatants to become confident enough about their future that they might demobilize. Direct engagement could also provide an opportunity to layout a code of conduct that might incorporate more specific operational issues rising from the work of military companies. Observation of companies such as EO to ensure that they adhere to basic principles of warfare is needed, something in which the International Committee of the Red Cross could take a lead.
The prospect that private military companies might gain some degree of legitimacy within the international community begs the question as to whether these firms could take on U.N. peacekeeping functions and improve on U.N. efforts. Military companies see this as an area of potential growth and are quick to point out the advantages they offer. There is no denying that they are cheaper than U.N. operations. EO cost Sierra Leone’s government $35 million for the 22 months it was there, versus a planned U.N. operation budgeted at $47 million for eight months. Likewise, its annual cost in Angola was a fraction of that of the U.N.’s operation–for example, in 1996-97, UNAVEM III cost $135 million. Admittedly, EO and other such firms provide military support, not peacekeeping, but there is no doubt that they can mobilize more quickly and appear less sensitive to casualties. However, accepting a U.N. mandate or conditions may also undermine a company’s effectiveness. As any soldier who has served in a U.N. operation will attest, a peacekeeping mission is only as effective as the operation’s mandate.
Give War a Chance
Policymakers and multilateral organizations have paid little attention to private-sector involvement in wars. Yet low-intensity conflicts — the type that military companies have specialized in up to now — will be the wars that prevail in the first part of the twenty-first century. Their virulence and random nature could undermine the viability of many nation-states. These wars defy orthodox means of resolution, thus creating the circumstances that have contributed to the expansion of military companies into this area.
Conflict resolution theory needs to look more closely at the impact of coercion, not dismiss it. Military companies may in fact offer new possibilities for building peace that, while not universal in applicability, can hasten the end to a war and limit loss of life. Moreover, there is no evidence that private-sector intervention will erode the state. Despite the commercial motives of military companies, their interventions, if anything, have strengthened the ability of governments to control their territory. Yet, military companies are unlikely to resolve conflicts in the long term. Political intervention and post-conflict peace-building efforts are still necessary.
Although the U.N.’s special rapporteur on the use of mercenaries has acknowledged the difficulties in equating military companies with mercenaries, the debate has not moved beyond that point. Admittedly, the U.N. is in a sticky position. Although some member states have condemned the use of military companies, others have employed their services or condoned their operations. Meanwhile, the future of private military interests looks bright. ”Now entering its eleventh year, MPRI has over 400 employees," declares the company’s Web site, noting that in 1997 the volume of business exceeded $48 million. Even with a mercenary label and its associated moral stain, EO and Sandline continue to tout their services to beleaguered governments. Other companies are likely to emerge that offer EO’s services, particularly in terms of low-key military training and advising for governments. The most rapid expansion is likely to be linked to the protection of commercial interests, although these can act as a springboard for more aggressive, military actions alongside local companies and power brokers. Mainstream companies, from the United States in particular, are also likely to encroach into low-intensity conflict areas. With backing from a cautious administration not wanting to fore-go strategic influence, the temptation to use military companies might prove irresistible.
Regulation of military companies will be problematic, given the diversity of their services and the breadth of their market niche. Yet, in many respects, the private military industry is no different from any other sector in the global economy that is required to conform to codes of practice — except that in the former’s case, the risk of political instability and social mayhem is amplified if more unscrupulous actors become involved. There is good reason to glance back in history to a time when private military forces operated more or less freely. Historian Anthony Mockler notes that one hundred years after the first condottieri entered Italy: "The lines had become crossed and tangled: mercenaries had become rulers and rulers had become mercenaries."
Want to Know More?
Mercenaries have been around for as long as warfare itself. For detailed accounts of their history, see Anthony Mockler’s Mercenaries (London: MacDonald, 1969) and Janice Thomson’s Mercenaries, Pirates & Sovereigns: State-Building and Extraterritorial Violence in Early Modem Europe (New Jersey: Princeton University Press, 1996).
Several recent articles and studies scrutinize private military companies and their activities worldwide: David Shearer’s Private Armies and Military Intervention, Adelphi Paper 316 (New York: International Institute for Strategic Studies, February 1998); William Shawcross’ ”In Praise of Sandline" (The Spectator, August I, 1998); Al J. Venter’s "Market Forces: How Hired Guns Succeeded Where the United Nations Failed" Jane’s International Defense Review, March 1, 1998); Ken Silverstein’s "Privatizing War" (The Nation, July 28, 1997); and David Isenberg’s Soldiers of Fortune Ltd.: A Profile of Today’s Private Sector Corporate Mercenary Finns (Washington: Center for Defense Information, November 1997).
The legal status of mercenaries is addressed in Francoise Hampson’s "Mercenaries: Diagnosis Before Prescription" (Netherlands’ Yearbook of International Law, No.3, 1991) and Edward Kwakwa’s "The Current Status of Mercenaries in the Law of Armed Conflict" (Hastings International and Comparative Law Review, vol. 14, 1990).
Martin van Crevald examines the changing dynamics of conflict in The Transformation of War (New York: The Free Press, 1991). Two studies provide empirical evidence that outright victory, rather than negotiated peace, has ended the greater part of the twentieth century’s internal conflicts: Stephen John Stedman’s Peacemaking in Civil Wars: International Mediation in Zimbabwe 1974-1980 (Boulder: Lynne Rienner, 1991) and Roy Licklider’s "The Consequences of Negotiated Settlements in Civil Wars 1954-1993" (American Political Science Review, September 1995).
On human rights, see a series of reports by the U.N.’s special rapporteur on mercenaries that are available online: Report on the Question of the Use of Mercenaries as a Means of Violating Human Rights and Impeding the Exercise of the Right of Peoples to Self-Determination.