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Myths of Hybrid Warfare

“[A]s Clausewitz stated nearly two centuries ago, although war changes its characteristics in various circumstances, in whatever way it manifests itself, war is still war. War in the twenty-first century has been and will remain a complex phenomenon, but its essence has not and will not change.“1  

The fact that the essence of war has not changed is a profound observation that has important implications for international law. The unchanged nature of war means that the core provision of the United Nations Charter prohibiting resort to military force is as binding today as it was when it was adopted in 1945. It does not mean, however, that nothing has changed. Clearly the computer revolution in military affairs has impacted tactics and weapons. International law includes mechanisms for dealing with such changes.  In brief, the core international law principles relevant to war are either timeless or have been modified over time as needed. 

Under international law, war or armed conflict exists when two or more organized armed groups engage in fighting of some intensity.2 The strategy, tactics, or weapons involved in fighting do not determine whether a situation amounts to armed conflict. This legal characterization determines whether peacetime law or the law of war applies. For example, the 1949 Geneva Conventions on the protection of victims of armed conflict apply only in situations of armed conflict or occupation. The most important of those protections, the right to life, is relaxed during armed conflict. Thus, it is imperative to know if an armed conflict exists or not.

Nevertheless, some international law scholars in militarily powerful states have, since the 1960s (and more emphatically since the end of the Cold War), sought to expand the legal right to resort to killing with military force. One variation of this argument focuses on certain tactics or new technologies. The claim is that non-state-actor armed groups are new and use new types of weapons and tactics that are outside current international law. Another variation claims that certain technologies such as cyber weapons are new and fall into a legal black hole. Without rules, the assertion is that governments are free to use these weapons according to their policy preferences. Some of the terms invoked in these arguments about the legal right to resort to force include “hybrid war,” “borderless war,” “asymmetric war,” “operations other than warfare,” “new kinds of battlefields,” and “irregular war.” What principally matters in international law, however, is whether the conflict is legally a war, not what sort of war.

The term “hybrid war,” for example, is clearly being used to attempt to open up space outside the restrictions of law. In distinction to Murray and Mansour’s view quoted at the outset of this article, the U.S. Army’s Field Manual 3-0 on “Operations” implies that there is something new about hybrid war that is unregulated:

“The future operational environment will be characterized by hybrid threats: combinations of regular, irregular, terrorist, and criminal groups who decentralize and syndicate against us and who possess capabilities previously monopolized by nation states. These hybrid threats create a more competitive security environment, and it is for these threats we must prepare.”3 

The implication of this statement is that a new form of warfare is emerging that is so dangerous as to necessitate using force in response. Omitted is the need to discern which threats are true military threats.

The remainder of this comment will consider three challenges to the Field Manual’s perspective: 

The factual premise that hybrid war is new and, therefore, unregulated in international law is incorrect. Combining unconventional or irregular tactics with conventional ones is as old as warfare.

Some aspects of warfare are new, but it is erroneous to think that international law is out of date or full of gaps with respect to new developments. 

Further, even if international law were deficient, identifying gap-filling rules must come from within the system of international law. In political science or other fields, it may be appropriate for scholars to offer their own personal proposals. In law, as in theology, reasoning must draw from recognized authority using accepted methods. 

Hybrid war is not new, and cyberspace is not unregulated

In their book on hybrid warfare, the military historians Monsoor and Murray recount the use of combined or “hybrid” tactics in ancient Greece, in colonial North America, in the Second World War, and in Vietnam. The book characterizes hybrid war as “conflict involving a combination of conventional military forces and irregulars[…] which could include both state and nonstate actors, aimed at achieving a common political purpose.”4 Miklaucic adds that the forces engaged in hybrid war “employ conventional and non-conventional means adaptively in pursuit of their objectives.”5  

The Ukrainian conflict that began when Russian troops took control in Crimea in February 2014 is being used as an example of hybrid warfare today. Again, it is a case which demonstrates that what is being labeled today as “hybrid warfare” is far from new. According to U.S. Army Special Operations Command, “Counter-Unconventional Warfare: White Paper,” Russia seems to be following the old Soviet principle of maskirovka – that of using “camouflage, denial, and deception to achieve desired effects.” Russia is plainly combining military and nonmilitary means in Ukraine from “bribery of opposing public officials [and] destabilizing propaganda” to “long-range artillery, microwaves, radiation, and non-lethal biological weapons.” Regular Russian troops are joining with irregular Ukrainian units to take the control from forces loyal to Kiev. 

Russia’s varied conduct in Ukraine can be termed as “hybrid warfare” when it is integral to the actual organized armed fighting that is occurring in Ukraine. In contrast, when observers label Chinese activities as hybrid warfare, they do so in error. China is not currently involved in any armed conflict. The United States military believes that, in the event of an armed conflict, China would employ an array of conventional and nonconventional means, including trade measures, commercial and financial arrangements, environmental manipulation, and psychological and propaganda campaigns. In a list of “hybrid threats,” the U.S. White Paper also includes “economic aid, cultural, and international law warfare.” It is unclear what “cultural warfare” might be, but it is clear that economic aid and international law should not be characterized as “warfare.” Doing so limits the legal right to engage in them and gives the impression that economic aid and international law can be used unlawfully. International law does not prohibit the use of international law or economic aid. It is always open to the US or other states to meet Chinese international law arguments or Chinese offers of aid with counterarguments and counteroffers. This conduct may coincide with and be used supportively in a war effort but is not “warfare” per se. 

The same erroneous view is being taken of Chinese activities in cyberspace. Some Chinese efforts are unlawful but none are properly labeled as “warfare.” Governments are engaged in three types of unlawful cyber activity: spying, theft, and property damage. Most governmental spying is unlawful under national law rather than international law. International legal protections against spying appear to reach only as far as protections for personal privacy under human rights law. As of the date of this article, the world has witnessed nothing that could be properly categorized as a “cyberwar.” In the Georgia–Russia conflict of 2008, organized armed fighting began after Georgia launched an attack on unsuspecting Russian troops deployed to police a ceasefire in South Ossetia. Russia responded militarily, invading Georgia and coming to within 30 kilometers (18.6 miles) of the capital. Both sides relied on computers for communications, in order to operate military vehicles and deploy weapons. Interfering with such computers is part of standard military tactics. In addition, both sides attempted to disrupt various government computer operations not directly linked to the armed conflict as well as media and financial websites. Some of this activity was likely unlawful as interfering with civilian as opposed to military activity or for failing the test of military necessity, which restricts attacks to those that can advance the military objective.

The “Islamic State” or ISIS is also more appropriately characterized under well-established international law categories. The heated rheto­ric that it is something wholly new is
unwarranted. ISIS emerged out of the wars following the 2003 Iraq invasion that have erupted in Iraq and Syria. It currently controls territory in both states, governing with ingenuity and brutality. The group can be compared with the ideologically driven Fuerzas Armadas Revolucionarias de Colombia (FARC) in Colombia as well as many other non-state actors that take and hold territory in civil wars. While ISIS uses the Internet for propaganda and conventional military control, no firm evidence exists that it has created a cyber weapon that can cause kinetic damage. It is also linked to terror attacks outside of its area of control including attacks in Paris on 13 November and Beirut 12 November. Terrorism is in almost all cases not war but criminal conduct. 

International law has the means to meet new challenges

As the above discussion shows, international law has rules governing even the newest technology of war, namely computers. The use of cyberspace for offensive tactics does not pose a serious challenge to current legal categories. Nevertheless, a good deal of the literature devoted to international security and cyberspace reflects a belief that international law has not kept pace and now has gaps. A further assertion is made that if no rule exists forbidding the use of a weapons or tactic, it is permitted. 

International law has plenty of foundational principles available to regulate injurious conduct in war and peace that can be applied to new technologies. Reasoning by analogy is also used international law, just as in domestic law. Moreover, international law includes among the three primary sources not only treaties and customary international law but also general principles of law. International courts and tribunals have drawn certain well-known general principles from surveying national legal solutions. 

Whether considering a foundation principle, general principle, or reasoning by analogy, the answers will lie in the law of peace, not the limited rules that prevail in armed conflict. Armed conflict is an exceptional situation, which only exists in the case of explicit evidence. The normal or default situation is peace. 

More specifically with respect to cyberspace, international law supports regulating cyberspace as an economic sphere and one of communications. When a state has been the victim of cyber theft, spying, or damage, international law contains means of responding lawfully, including with coercive means. The same sort of coercive measures that are lawful to use against economic wrongs and violations of arms-control treaties will generally be lawful to use in the case of a cyber attack. In the economic sphere, coercive responses to violations tend to be known as “countermea­sures”; in arms control, such countermeasures are commonly known as “sanctions.” When a state has clear and convincing evidence that a cyber injury is attributable to a foreign sovereign state, the victim state may itself commit a wrong against the responsible state, so long as the wrong is proportional to the initial wrong and aims at ending the wrong or procuring a remedy. In most cases of cyber injury, the evidence will come after the act is over or the damage is done. This fact indicates that the appropriate remedy will be financial compensation. 


Warnings of new threats requiring military responses are not new. Today the warnings sometimes employ the term “hybrid war.” We read assertions that no law exists respecting new threats. Instead of relying on law, therefore, the argument is that we should place our faith in military force. It is an argument based on two levels of false assertion. In fact, hybrid war is not new. Moreover, international law comprehensively regulates conduct that can injure, including activity in cyberspace. Greater security will come from respect for authentic international law, a code shared by all nations, faiths and ideologies and devoted to the preservation of peace.

1 Peter R. Mansoor, Introduction, Hybrid Warfare in History, HYBRID WARFARE, FIGHTING COMPLEX OPPONENTS FROM THE ANCIENT WORLD TO THE PRESENT 1 (W. Murray and P. Mansoor eds., 2012)

2 See International Law Association, Final Report of the Use of Force Committee: The Meaning of Armed Conflict in International Law 8 (August 2010), available at and WHAT IS WAR? AN INVESTIGATION IN THE WAKE OF 9/11 (Mary Ellen O’Connell ed., 2012.)

3 “Hybrid Warfare,” in: JSOU Report 13–4 (2013), p. 4, quoting Headquarters, Department of the Army, Army Field Manual 3-0: Operations (Washington, DC: Department of the Army, 2011), p. 14.

4 Cf. Salonius-Pasternak, Charly (2015): “Preparing Finland for hybrid warfare,” in: FIIA Comment 6/2015.

5 Miklaucic, Michael (2011), “NATO Countering the Hybrid Threat,” NATO Allied Command Transformation. (accessed July 1, 2015). Also see United States Army Special Operation Command, “Counter-Unconventional Warfare: White Paper” (2014) (accessed July 1, 2015).



Professor Mary Ellen O’Connell is the Robert and Marion Short Professor of Law and Research Professor of International Dispute Resolution – Kroc Institute for International Peace Studies, University of Notre Dame, USA. Her recent publications include “21st Century Arms Control Challenges: Drones, Cyber Weapons, Killer Robots, and WMDs,” (13 Wash. U. Global Stud. L. Rev. 515, 2015); “Chapter One: Historical Basis and Legal Development” (The Handbook of International Humanitarian Law, 2013) and “What Is War? An Investigation in the Wake of 9/11” (Brill/Nijhoff, 2012). She chaired the International Law Association’s Committee on the Use of Force from 2005 to 2010 and was a vice president of the American Society of International Law (2010-2012.) Professor O’Connell is a member of the German and European Societies of International Law and the International Institute of Humanitarian Law—San Remo. She was a professor at the George C. Marshall European Center for Security Studies, Garmisch-Partenkirchen (1995-1998).