Symposium on PMSCs: The Role of PMSCs in the Proliferation of Weapons and Implications under Arms Control Mechanisms

[Manon Blancafort is a project assistant at the Small Arms Survey and previously served for three years as an operational reservist in the French Air and Space Forces, within a Protection Squadron.

Callum Watson is the gender coordinator and programme manager at the Small Arms Survey.

Florence Foster is a senior project manager at the Geneva Academy of International Humanitarian Law and Human Rights.

Jowita Mieszkowska is a legal adviser at TRIAL International.]

The past decades have been marked by record military spending – highest global total ever recorded by the Stockholm International Peace Research Institute (SIPRI), and the 10th year of consecutive increases, the increasing privatisation of security and outsourcing of military functions in both conflict-affected and non-conflict settings, and the privatisation of the arms industry itself. Private Security Companies (PSCs) and Private Military Companies (PMCs) (together referred to as PMSCs) now perform a wide variety of functions, including recruitment, training, logistics, strategic counsel, direct combat, and critically, arms procurement. In addition, PMSCs have become global players in the arms trade, with some becoming entangled in illicit markets and financing networks.

Consequently, some PMSCs can now be found at the heart of international arms flows, often operating in under-regulated spaces, raising significant concerns over the enforcement of existing frameworks, their potential shortfalls, along with accountability and access to justice for civilian populations often put in harm’s way.

Against this backdrop, what role do PMSCs play in the proliferation and control of weapons? What does the regulatory toolbox look like? How does the inclusion of weapons-related provisions in the draft international instrument on PMSCs, particularly in its Revised Fourth Draft, shape the scope and ambition of ongoing regulatory efforts? And critically, what is the role of the arms control community in addressing these challenges?

What is the Role of PMSCs in the Proliferation of Weapons?

There has been mounting concern over documented instances in which PMSCs have been implicated in illicit arms transfers and the misuse of weapons, increasingly involving small arms, echoing violations similar to those historically committed by states. Increasingly, recurring patterns show that certain PMSCs contribute to the circulation of small arms in contexts affected by armed conflicts and other situations of widespread violence, often in defiance of arms embargoes and amid weak or poorly enforced weapons management systems.

Investigative reporting and UN expert panel reports have uncovered numerous cases in which PMCs have circumvented arms embargoes or exploited legal loopholes to supply weapons. Notable examples include Libya, where contractors operating under the guise of security assistance delivered military hardware, in direct violation of the UN arms embargo. Similar patterns have emerged in Mali. In parallel, PMSCs may also acquire their weapons from domestic suppliers, such as gun shops. Exports of, for example, firearms to the civilian market,  can be subject to less stringent licensing requirements compared to military-grade procurement.

In some such cases, these diversion operations rely on complex networks of offshore shell companies and brokers, obscuring accountability. Brokers and intermediaries, sometimes operating in partnership with PMSCs, have been found to exploit gaps in export control systems and differences in national licensing requirements, forge end-user certificates or move weapons through unregulated or free trade zones for trans-shipment, storage, and redistribution. The result is a supply chain that is not always transparent, and at times, intertwined with organised criminal actors.

Although most PMSCs steer clear of illicit markets, often to safeguard their business interests, there are documented cases of PMSCs being directly involved in arms trafficking and other forms of transnational crime, including resource exploitation, drug trafficking, cyber fraud, and the provision of intelligence services—to sustain their operations. Such patterns have been seen in the Central African Republic, for instance. There is also evidence that this has occurred alongside or with the support of state actors, who also play a key role in global arms proliferation.

Beyond military contexts, Private Security Companies (PSCs) have increasingly supplemented public policing functions in many states around the world. While some jurisdictions restrict their use of firearms, others permit PSCs to operate while armed, contributing to ongoing debates over the use of “less-lethal” weapons such as tasers—as seen, for example, in Chile.

These gaps are further compounded by the lack of uniform global standards regulating the acquisition, possession, and transfer of arms by private security actors. Additionally and as the industry evolves, PMSCs are expanding into new technological frontiers. Emerging trends include the acquisition and use of dual-use technologies, unmanned systems, and cyber capabilities, raising new oversight challenges. Current regulatory frameworks, still largely focused on traditional military and security services, risk falling behind the pace of industry transformation.

As major end-users – and, increasingly, as suppliers and intermediaries – of firearms and security equipment, PMSCs now represent a significant node in the global arms trade. This broad role underscores the pressing need to assess and strengthen the regulatory frameworks that govern their weapons-related activities.

What are the Regulations Governing PMSCs and Weapons?

At the moment, several international and regional regulatory instruments exist to control, regulate and manage weapons and ammunition production, sale, export and transfer inter alia to “promote the establishment and maintenance of international peace and security with the least diversion for armaments of the world’s human and economic resources”—and place the responsibility and obligation of arms control firmly on States.

The Arms Trade Treaty (ATT) is the sole legally binding international treaty that governs the trade of conventional weapons. However, it is binding only on States and its application to non-state actors, including the private sector, relies on national implementation by States Parties. The binding UN Firearms Protocol, supplementing the Convention against Transnational Organized Crime (UNTOC), offers an important yet underutilized tool for addressing the role of PMSCs in arms proliferation. While the UNTOC and the Firearms Protocol require States to criminalise the illicit manufacturing and trafficking of firearms, their parts, components, and ammunition, as well as organised criminal activity, their application is limited—they are crime prevention tools applicable to a sub-category of weapons.

In Guatemala, private security companies hold approximately 15% of registered firearms but are responsible for 35% of reported lost or stolen weapons, a pattern that underscores the leakage risks and reflects trends seen in other regions. The ATT’s Article 11, which focuses on preventing diversion, and Article 5, which calls for national control systems, provide an entry point for States to enhance oversight and explicitly regulate arms transfers to PMSCs in domestic law.

When looking at non-legally binding instruments, technical standards such as MOSAIC (a set of voluntary, practical guidance notes), developed in support of the UN Programme of Action (PoA) and the International Tracing Instrument (ITI), include detailed provisions on arms marking, tracing cooperation, and twenty-year record retention. Again, their application to PMSCs remains limited as compounded by the fact that stockpile security and weapon assignment practices among PMSCs diverge considerably from the military chain-of-custody model, and there is little regulation concerning the repatriation or return of weapons once contracts end. In effect, this regulatory vacuum leaves open pathways for diversion and trafficking.

Last but not least, the Security Council can sanction and impose arms embargoes (Article 41 of the UN Charter) on States but also businesses. However, their practical leverage over non-state actors like PMSCs is determined by the political will and regulatory capacity of the states in which they operate, and their corresponding expert review panels.

Arguably each in their own way, current international frameworks lack sufficient detail and enforcement throughout the weapons life-cycle to fully regulate activities such as authorization, licensing, marking, tracing, and end-use control when it comes to PMSCs; nor have they sufficiently adapted to the sharp increase in weapons outside of state-owned structures.

The Wagner Group, and its successor Africa Corps, has been accused of “attempting to obscure its efforts to acquire military equipment for use in Ukraine, including by working through Mali and other countries where it has a foothold” and using “false paperwork for these transactions”, exploiting the abundance of arms in Mali. This demonstrates a gap in the effective implementation of the ATT, to which Mali is a party. Separately, Wagner has also been accused of supplying Sudan’s Rapid Support Forces with missiles for its conflict with the Sudanese army.

More specifically, key political instruments regulating Private Military or Private Security Companies and Private Security Service Providers, have only had limited impact in addressing arms flows. While both the Montreux Document and International Code of Conduct for Private Security Service Providers (ICoC) do include useful references and outline best practices, especially on weapons management and training, those instruments are non-binding. Moreover, companies engaging in illicit practices involving arms can simply relocate outside of the Montreux Document’s 59 participating states, and would be unlikely to sign the ICoC.

Finally, the UN Guiding Principles on Business and Human Rights (UNGPs), the global authoritative normative framework governing responsible business conduct, apply to all businesses, regardless of size or sector, including PMSCs. Through human rights due diligence, companies should ensure that they are not causing, contributing or being directly linked to adverse human rights impacts. The principles apply equally to PMSCs – their use of weapons or role in arms proliferation – as well as to the broader ecosystem of companies—including clients, arms manufacturers, brokers, financiers, logisticians, and advisers—that help sustain them. In certain jurisdictions, the UNGPs have been transposed into law.

How Could a Future PMSC Instrument Close the Gap?

Work is currently underway on a potentially legally-binding instrument on the regulation of PMSCs. The latest draft by the Open-Ended Intergovernmental Working Group on PMSCs—their Revised Fourth Draft—reflects growing concern over PMSC involvement in weapons proliferation: references to weapons appear in Preambular Paragraph 8 (PP8) and more substantively in Article 11. This draft recognizes the multifaceted roles PMSCs may play in arms proliferation as suppliers, intermediaries, or end-users, thereby expanding the traditional arms control framework to include corporate actors traditionally outside formal treaty obligations. By including obligations on access to justice and victim remedies, it also broadens the arms control scope to encompass accountability for human rights violations—a notable shift from conventional treaty models focused solely on supply chain control. However, despite its ambitions, Article 11 remains problematic in its current form. It inconsistently uses the terms “weapons” and “conventional arms”, fails to account for diversion, and wrongly combines the restrictions in ATT Articles 6 and 7 into one incoherent clause. Critically, there is currently little to no political momentum behind the initiative, let alone engagement from arms control experts with regard to this Article.

In many countries, outdated private security laws lacking a gender perspective hinder authorities’ ability to track and address cases of SGBV committed by private security personnel. While countries like Argentina have created a National Registry of Femicides that records the number of femicides perpetrated by PSC personnel, few regulatory frameworks around the world systematically mandate public reporting of sex-disaggregated data on incidents involving SGBV, making it nearly impossible to monitor patterns effectively. This institutional opacity is often exacerbated by fragile accountability mechanisms and weak state oversight mechanisms. Consequently, abuses committed by private security personnel, including the misuse of firearms, frequently go unreported and unaddressed, reinforcing cycles of impunity and eroding public confidence in both private security providers and the broader justice system.

The challenge in preventing the harm that comes from PMSCs’ involvement in arms proliferation—as suppliers, intermediaries, or end-users—is not simply due to a lack of regulatory mechanisms. Existing mechanisms do go some way in addressing these issues. Weak implementation and enforcement remain the main Achilles heel, hampered by a lack of access to information and standing to challenge licensing decisions, prolific national security exemptions, and a failure of States to enforce existing expected standards of conduct and practice.

Addressing these challenges requires coherent, collective national and international action to ensure that current frameworks are adapted to remain relevant to the evolving realities of privatized security and warfare. Indeed, regulatory efforts in the making—such as the instrument on PMSCs—present a timely opportunity that should be seized to close critical gaps. Engagement and political capital in this latter process are critical to ensure its content is meaningful and that the instrument can address, to the best extent possible, evolving trends. More specifically, the arms control community should critically engage with this process and provide technical input to Article 11, ensuring that it is fit for purpose.

More broadly, sustained, evidence-based engagement is needed to understand and address the risks. This could include research institutions to inform targeted oversight strategies by identifying regulatory blind spots and promoting harmonized approaches – such as the Small Arms Survey that map global patterns of small arms diversion involving PMSCs; or others that could provide comparative research on national frameworks governing civilian firearms access by PMSCs. Practical tools could also be developed to support states in regulating and monitoring firearms acquisition and use by PMSCs, building on established instruments such as the ATT, the Firearms Protocol, and MOSAIC. Finally, engagement by academic institutions and international law and arms control experts remains critical to accompany the development and interpretation of existing and developing international frameworks. These initiatives would require dedicated funding and donor support, but together, they could contribute meaningfully to strengthening oversight of PMSCs.