Soldiers of Fortune: Why U.S. Mercenaries Should Not Be Legal

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Early in the morning of July 7, 2021, a heavily armed group entered the home of Haitian President Jovenel Moise and killed him in his bedroom. The assailants, reportedly dressed as U.S. Drug Enforcement Administration agents, were well-trained, organized, and appear to have received significant financing for the assassination. Haitian authorities have made a number of arrests in connection with this event, including of two U.S. citizens, though the parties primarily responsible for this assassination — and the precise motive — currently remain under investigation.

If the two Americans arrested in Moise’s assassination are found guilty, they will have clearly broken Haitian law. However, they may not have broken U.S. law. Under current laws and regulations, it is not illegal for a U.S. citizen to provide combat services as a foreign mercenary fighter. The closest legal prohibition to U.S. mercenaries might be found in the Neutrality Act (18 U.S.C. §960). This statute, however, prohibits only acts carried out “within the Unites States” as part of a military expedition against a friendly country. Which raises the question: Should it be legal for U.S citizens to provide services as a paramilitary fighter against a foreign country? After all, this type of dangerous work is often contrary to U.S. national security interests.



Countries around the globe (e.g., the United Kingdom, France, Germany, and South Africa) have domestic laws that restrict their citizens from serving as foreign mercenaries. While an argument might be made that U.S. citizens should be free to join in foreign conflicts as a matter of personal choice or conviction (as many did during the Spanish Civil War, for instance), I’d submit that in light of broader national security interests, the United States should take affirmative action in restricting U.S. persons from selling their services as foreign fighters.

To address this hole in the law, the Biden administration should amend U.S. export regulations to expand the definition of “defense services” to cover U.S.-based mercenaries. An amendment to arms trafficking regulations might also be an effective and practical approach, as opposed to seeking to pass a new statute via Congress. Having devoted years to national security prosecutions as a career federal prosecutor, I view U.S. mercenary conduct as equivalent to the illegal supply of U.S. weapons to a foreign party. The uncontrolled supply of weapons to foreign end users is contrary to U.S. national security interests as it can lead to local and regional instability. The government regulates the export of U.S. origin weapons for that reason, and the law should do the same for U.S.-origin combatants. Both weapons and combatants can pose a real and present danger to U.S. national security interests.

The History of Mercenaries

Mercenaries have a long, controversial history in international conflict, reaching back at least 3,000 years to the Egyptian empire under Ramses II, and they were later frequently used by the Greek and Roman empires. A “mercenary” has been defined by a U.N. convention as a non-national person acting to overthrow a government or undermine the constitutional order of that nation motivated by private gain or material compensation. Britain’s use of Hessian mercenaries in the American Revolutionary War is part of the country’s lore. Spanning the last century alone, foreign mercenaries were employed in conflicts in Africa, the Middle East, the Americas, and Southeast Asia. Mercenaries have often been employed to overthrow unstable governments in developing counties and provide the critical manpower (often with a limited number of combatants) for many small-scale coup d’états.

The International Convention against the Recruitment, Use, Financing and Training of Mercenaries (the U.N. Mercenary Convention) came into force in 2001. As noted at the time of the debate on this resolution, the convention represented an important effort by the international community to limit the harm and injury employing foreign fighters to support violent conflicts causes to civilian populations. This is, in many ways, analogous to the 1982 U.N. Convention on the Law of the Sea, which — among other things — prohibits piracy, whether state-sponsored or by irregular partiers. The U.N. Mercenary Convention declares that the use and financing of mercenaries in armed conflicts represents an offense. Ratified by 35 member nations, the United States, Russia, and China have not ratified the treaty. The United States has not ratified the treaty in part due to the perception that prior U.N. protocols and resolutions on this topic have included different, if not conflicting, definitions and possible applications. In addition, some nations have argued that private military companies should be covered by the mercenary definition. Lastly, given that that only 35 counties have ratified this convention, there exists a question as to whether ratifying it would have a meaningful substantive effect in creating an accepted norm of international law. Accordingly, the U.S. government may have simply decided that inaction was the better course to take, at least until a majority of other countries (and the major powers) were willing to commit to banning mercenaries.

Several countries have enacted domestic laws that restrict or prohibit their citizens from recruiting, financing, or serving as mercenaries in foreign-based conflicts. In Germany, for example, it is an offense for a citizen to join the armed forces of or a comparable armed association in a foreign state absent the approval of the Ministry of Defense. In France, it is illegal for a citizen to be recruited or to act as a fighter in another nation’s armed conflict for personal benefit, or to act in hostilities or participate in acts of violence aimed at the overthrow of the governmental institutions of another state.

No U.S. law currently restricts or prohibits U.S. persons from serving in a foreign mercenary force. Only the U.S. government is restricted from hiring mercenaries under what is known as the Anti-Pinkerton Act of 1893. The Fifth Circuit interpreted this statute in a 1977 decision as prohibiting the government from using any organization that offers “quasi-military armed forces for hire.” The U.S. government, however, is not restricted from employing private businesses that provide security services (also known as “private military companies” or “PMCs”) like those used in Iraq and Afghanistan. Mercenaries (as commonly defined) are generally individuals serving in foreign combat roles for money, while private military companies are legally formed entities contracted by governments for specific security related services.

As to individual U.S. citizens, one statute that is part of the Neutrality Act makes it illegal for any person “within the United States” to take part in “any military or naval expedition or enterprise” carried out from the United States against a friendly country. Court decisions have held that this law is designed to prohibit “the use of the soil or waters of the United States as a base” for unauthorized military expeditions against friendly foreign powers. Attorney General Robert Kennedy declared in 1961 following the Bay of Pigs attack, “[t]here is nothing criminal in an individual leaving the United States with the intent of joining an insurgent group.” As written, unless there is evidence of any domestic act, the Neutrality Act does not prohibit a U.S. mercenary from acting outside of the United States.

A Possible Legal Solution

The law that comes closest to applying to individual mercenaries is the Arms Export Control Act (“AECA,” 22 U.S.C. § 2778 et. sec.) and the International Traffic in Arms Regulations (“ITAR,” 22 C.F.R. Parts 120-130). Under the International Traffic in Arms Regulations, it is illegal to export from the United States a wide range of “defense articles” (military technology and technical data) or provide “defense services,” such as conducting military training, on behalf (or for the benefit) of any foreign person or forces (“regular or irregular”) without a State Department export license. It is illegal to provide a defense service without a license “whether in the United States or abroad.” Thus, unlike the Neutrality Act, there is no requirement for prosecution under the International Traffic in Arms Regulations that any of the service be provided “within the United States.” A willful violation of the regulation carries a maximum penalty of 20 years imprisonment and a $1 million fine.

Export control regulations have been effective in controlling the flow of military technology from the United States to foreign end users in Russia, China, Iran, Libya, Thailand, Syria, and North Korea; to rebel and insurrectionist groups (such as the Tamil Tigers); to terrorist groups such as Hizballah; and to various private international arms brokers (e.g., the notorious Russian arms dealer Viktor Bout). U.S. persons have also been prosecuted under the regulation for illegally providing a “defense service” to foreign persons.

Proposed Amendment to the International Traffic in Arms Regulations

The International Traffic in Arms Regulations definition of a “defense service” does not cover hired mercenary services in foreign conflicts. An amendment to this definition as a regulated “export” could address this concern.

Specifically, the definition of a “defense service” contained in 22 C.F.R. § 120.9(a)(1) that covers “furnishing of assistance” could be amended to include providing personal services, or material support, as a combatant to (or for the benefit of) a foreign power, person, or military force (“regular or irregular”). Alternatively, a new Section 120.9(a)(4) could be added to specifically include providing personal services as a foreign fighter, or otherwise providing material support to foreign parties or forces, as a “defense service” requiring an export license.

Amending Section 120.9(a) is consistent with the objectives of the International Traffic in Arms Regulations in controlling arms trafficking (and defense services) and the broader concept of prohibiting material support to terrorists (in this case, foreign regular or irregular forces). This could address the threat to U.S. national interests from U.S. origin mercenaries supporting foreign forces involved in both localized coup d’états and ongoing larger conflicts such as those in eastern Ukraine or Syria. Regulating mercenaries as a defense service could also cover a range of foreign combat conduct not covered by Section 2339A. As with other International Traffic in Arms Regulations regulated conduct, this approach would allow the government to approve or reject a “mercenary export license” on its specific merits and on a case-by-case basis.

The Status Quo Isn’t Good Enough

Arguments against amending the International Traffic in Arms Regulations “defense service” definition could range from substantive concerns to technical objections. First, some might ask, shouldn’t the primary objective be the enactment of a stand-alone statute adopting the U.N. Mercenary Convention into domestic law to prohibit mercenary activities (or otherwise follow the examples of France or Germany)? It’s better to legislate a new law prohibiting or limiting mercenaries than to use the administrative or regulatory process. For example, look to the number of U.S. criminal code statutes adopted to conform to other U.N. resolutions or treaties, such as those prohibiting the production and use of biological and chemical weapons.

While this might represent a good legislative means to the desired end, it doesn’t have to represent a binary choice. The International Traffic in Arms Regulations serves to implement the language of the Arms Export Control Act that in “furtherance of world peace and the security and foreign policy of the United States, the President is authorized to control the import and the export of defense articles and defense services.” A modest expansion of the International Traffic in Arms Regulations definition of a “defense service” to (logically) include the “export” of combat services is entirely consistent with an existing statute. Congress clearly remains free to enact any relevant substantive law at any point in the future.

Secondly, tinkering with the International Traffic in Arms Regulations definition of “defense service” could risk opening all of the existing legal government contractor defense security businesses and their employees to potential criminal liability. I’d suggest that this really is a straw man argument, given that those organizations that provide foreign services (training, etc.) already are regulated under the International Traffic in Arms Regulations (22 U.S.C. § 2752). In addition, private military companies operate as legally formed and licensed businesses that obtain government authorization for their activities through the contract process. Thus, the International Traffic in Arms Regulations would apply only if and when any private military contractors or their employees might engage in some non-licensed “defense service” of a mercenary nature.

Another objection might be that “if it ain’t broke, don’t fix it” with more unnecessary laws and regulations. After all, the actual number of freelancing, marauding U.S. mercenaries has to be minimal. However, this assumes we truly know that mercenary activity is de minimis and, more importantly, believe that mercenary conduct (condemned around the world for its harm) is neither harmful nor a risk to U.S. national security interests (or at least is at an acceptable level). If the risk attendant from mercenary conduct (existing or in the future) to U.S. interests is real, however, it should merit action.

Looking Ahead

The International Traffic in Arms Regulations exists to restrict the flow of military technology and weapons — and associated defense services — from the United States to hostile foreign powers, non-state actors, and opportunistic brokers looking to profit from foreign instability and conflicts. Under these regulations, government permission is required before U.S. citizens can provide any “defense service” in the form of combat training to foreign parties. Yet, there is no legal restriction on U.S. citizens travelling abroad to actually engage combat for hire in foreign conflicts. It is time to correct that gap in the law.

The recent attack in Port-au-Prince by mercenaries that killed Haitian President Moise is a stark reminder that even the most forceful U.N. resolution or treaty still is dependent on each member nation adopting effective domestic laws. Currently, there is a clear absence of any substantive domestic U.S. law that restricts U.S. citizens from serving abroad as foreign fighters. The question now for policymakers is whether to continue with this status quo in which U.S. citizens are free to serve as foreign mercenaries for hire around the globe. Or should the current effective arms trafficking regulations be amended to include private foreign combat by U.S. citizens as a regulated “defense service”? The first option is fraught with risks to U.S. national security interests. If the International Traffic in Arms Regulations currently controls both the export of weapons and technical data, and personal services relating to military training and development, why not include as an equally important provision — the export of mercenary services? The risks such unregulated private paramilitary conduct poses to U.S. foreign policy interests greatly outweigh the value of any “personal freedom” to engage in armed combat anywhere for personal profit.



Will Mackie has served for thirty years as a federal prosecutor with the Department of Justice, both as an assistant U.S. attorney and a senior trial attorney with the National Security Division, Counterintelligence and Export Control Section, overseeing numerous counterproliferation, export control sanctions, and arms trafficking investigations and prosecutions. He currently is an adjunct law professor teaching national security related topics at Washington & Lee University School of Law.

Image: Wikicommons (“Retreat of the ten thousand” by Adrien Guignet)