Skip navigation

"Hybrid Warfare" and the Continuing Relevance of the Just War Tradition in the 21st Century

Before we can answer the question as to what rules can or should apply to “hybrid warfare,” we need to clarify what we actually mean by this term. What is the difference between “warfare,” as it is normally understood, and “hybrid warfare”? What, if anything, makes it distinct from other forms of conflict in such a way that a new or different normative framework might be appropriate?1

In 2009, Russell Glenn suggested that a hybrid threat can be characterized as such when “an adversary [...] simultaneously and adaptively employs (1) political, military, economic, social, and information means, and (2) conventional, irregular, catastrophic, terrorism, and disruptive/criminal warfare methods.” This process could involve a combination of both state and non-state actors.2 This would suggest an extremely complex form of warfare, difficult to pin down or define adequately. In 2009, US Secretary of Defense, Robert Gates, described the problem in “Foreign Affairs” when he articulated, “the categories of warfare are blurring and no longer fit into neat, tidy boxes. One can expect to see more tools and tactics of destruction – from the sophisticated to the simple – being employed simultaneously in hybrid and more complex forms of warfare.” Gates continued, “What is dubbed the war on terror is, in grim reality, a prolonged, worldwide irregular campaign.” Some on the panel at a discussion in Berlin on this subject orga­nized by zebis in July 2015, were very skeptical about the term “hybrid war,” arguing that war can manifest itself in many different ways but that it is still war. Concerns were raised that the new nomenclature was dangerous insofar as it allowed distinctions to be drawn that were invalid and exceptions to the normal rules to be made that should not be made. But, clearly, even if hybrid warfare is not as novel or different as some would argue, the type of conflicts that we, in the West, are currently engaged in, however they are defined, do look rather different to those that were experienced in the 20th century. 

The character of contemporary conflict, if not the nature of war, appears to be changing and this in turn raises questions about the suitability of normative frameworks that are supposed to govern it. Can something like the just war tradition, firmly grounded in traditional and arguably outdated understandings of conflict, really cope with the realities of contemporary warfare? Can it truly cope with things like ongoing terrorist activity carried out by non-state actors, or methods of causing harm that are predominantly nonlethal such as subversion or economic attrition? If the activity is not obviously war, then what can something like the just war tradition offer us? Do we need a new normative framework to go along with the new strategic challenges that we are facing? This, of course, is not simply a matter of semantics. Military practitioners around the world are keen to be able to understand and make sense of their professional activities within a coherent normative structure.3 When things change, they seek answers so as to ensure that their actions remain ethically justifiable. For precisely this reason, such questions have been asked before. For example, the advent of nuclear weapons led to much soul-searching about whether it was even possible to have morality in warfare anymore. In the 1990s and early 2000s, when peacekeeping, peace enforcement, and “operations other than war” were in particular vogue, people tried to fill the apparent gap between a normative framework that has evolved in order to guide thinking about war, and the reality of situations which were not war, but were not really peace either. Arguably, the growth in interest in International Humanitarian Law rather than the Law of Armed Conflict and the increasing influence of the “revisionist just war theorists” reflect the current unease at the relevance of traditional normative constructs in the face of contemporary challenges. 

The just war tradition has evolved over several millennia and is normally broken down into a number of related but discrete criteria. Looking at these, and the martial focus of the wording, suggests immediately why some believe this framework is not the right one for the current environment. The jus ad bellum criteria are normally concerned with what is required to justify going to war in the first place, while the jus in bello criteria are focused upon what may be done within war, and against whom. While the list can vary from source to source, most would not find the following selection particularly controversial:

Jus ad bellum criteria

• Just cause – that there is a genuine reason for the action, limited to self-defense, or protection of others

• Legitimate authority – declared by an actor who is genuinely able to speak for and represent a political community

• Right intention – that one is not only doing the right thing, but also doing it for the right reasons

• A goal proportional to the offence – an unlimited response to a limited injury cannot be justified

• Reasonable prospect of success – the actions must be capable of making the situation better, and there is a clear idea of what that “better” situation looks like

• Last resort – everything that could work instead has been given a chance

Jus in bello criteria

• Proportionality – do not cause more harm than is absolutely necessary

• Discrimination (also referred to as “distinction” in legal terms) – only deliberately harm those who have made themselves liable to harm through their actions

Why would one want to make a distinction between the two levels of war? It allows us to draw a line between spheres of moral responsibility – in this case, the decision to go to war and the actual conduct of that war. So, for example, soldiers are not responsible for the decision to go to war, but they are responsible for its conduct. Very senior military officers may straddle the line, but, as Michael Walzer points out in his classic book “Just and Unjust Wars,” this means we know pretty well where that line should be drawn. While the just war tradition is not necessarily about providing a set of easy answers, what it can do is help to structure decision-making by pointing to the factors that should be considered before and during any use of armed force.

However, to assume that the just war tradition cannot apply, because the situation is not war as we have historically understood it, is to allow those titles to obscure what is going in, and to confuse what the purpose of the tradition actually is in the first place. While the just war tradition historically evolved out of an effort to apply normative thinking to the taking of life – when it might be justified, in what type of cause, etc. – the moral reasoning contained in the tradition can be applied in a variety of other situations as well. The reasoning, if not the labeling, can be applied to any situation in which one was seeking to do something that would normally be prohibited. So, for example, intentionally hurting someone else – this is something that is universally prohibited under normal circumstances, but may become permitted, or even expected in different circumstances, such as disarming an attacker threatening school children. That hurt or harm, in war, is normally associated with death or injury, but there is no reason why it must only be connected to this very specific type of harm. It can just as easily be applied to when it might be acceptable to deprive someone of their freedom, damage or confiscate their property, corrupt their online data, or invade their privacy. All of these actions involve harm and are normally prohibited, but certain contexts may make them ethically justifiable. The just war tradition, despite the name that it has taken on over the millennia, provides a structured approach to decision-making in such situations.4 As such, it can provide useful guidance in war and peace, or any situation between the two such as peacekeeping, where an ethical framework is sought to help make a decision about what it is ethically permissible to do.

So, for example, one of the challenges that hybrid war is supposed to pose is connected to the type of messy “social” attacks that involve nonuniformed and unattributed actors, perhaps motorbike gangs carrying out criminal activity or agitators causing unrest, fomenting riots in the street to undermine the state’s legitimacy and ability to govern. However, even if such a strategy does not fit into normal conceptions of war – but instead involves promoting disobedience, undermining legitimate political processes, spreading false information, lying, deceiving, and sometimes simply doing harm – the reasoning found in the just war tradition can still help guide what it is acceptable to do in response to what kind of threat and against whom your actions may be directed. If one is considering clamping down on the use of social media, incarceration without charge of those deemed to be a threat until a situation has calmed down, or the restriction of the right to assemble, all of these actions involve “harm” and would not normally be considered acceptable. In that sense, it is about the following issues: whether or not an exception to the usual rules can be made, is the threat of harm significant enough to warrant an exceptional response, who has the right to impose such restrictions, will they actually work, is there anything else that might work instead, against whom should it be applied, and for how long?

The same type of reasoning can be useful elsewhere as well – from peacekeeping to counterespionage. So for example, even if we accept that espionage itself is not “war” in the conventional sense, it is still a method or strategy that involves disobedience, lying, deception, and sometimes, therefore, the doing of harm to others. The moral reasoning found in the just war tradition demands that such actions can be done only if there is a compelling, morally justifiable reason, that it is done with the right intentions, authorized by those who have the legitimacy to sanction the suspension of the normal rules, that any subsequent short- or long-term harm is proportional to what is at stake, that there is a reasonable prospect for success, and that there are no alternative options that might have an equally good chance of succeeding but would result in doing less harm.

Just because the title of the tradition appears to limit its usefulness in the contemporary security environment, the moral reasoning it represents is actually a very useful set of criteria, despite the wording, that can be applied in a much broader set of contexts than might initially be imagined. If one poses these questions and finds the answers unconvincing, there is clearly a legitimacy problem. If one or more criteria cannot be answered at all, then there is a very clear warning sign that the current path or specific action should be reconsidered immediately. This reasoning applies to hybrid warfare, peacekeeping, or any other situation in which one is seeking to make an exception to the normal rules.

Were we to simply abandon the just war tradition, and the several thousand years of thinking that has shaped its evolution in favor of something new and bespoke for the current security challenges, we would find ourselves producing a very similar list of necessary conditions for justification. The key questions the tradition asks about issues such as just cause, right intention, legitimate authority, last resort, and proportionality, are, at the very least, aspects that should be considered before breaking any “normal” rule and would seem to be even more pertinent when considering acting so as to consciously harm others. We would also need a new framework that would help us decide the way in which the exception should be carried out, by seeking to limit the necessary harm to those who in some way have made themselves liable, and that any harm to innocent parties is nevertheless limited as far as possible and is proportional to what is trying to be achieved. That is what the reasoning inherent within the just war tradition already provides; the context may change, but the principles remain relevant.

What about if the other side refuses to abide by the same rules, or even deliberately uses them against us? Are there situations in which it is permissible or even necessary to set aside the conventional normative framework in order to fight on an even footing? There are some who have argued precisely this, as they claim that the situation we find ourselves in today is unprecedented and the rules that we have to govern our behavior in response to such threats are unsuited to the foe and the situation that we are now faced with. As the daily news reports attest, in addition to deliberately targeting noncombatants, many opponents are also deliberately creating a situation of moral asymmetry: they do not seem to care about public criticism and deliberately violate the rules of war to try and force a reaction that will also go against the rules but, in doing so, will undermine our own legitimacy. In basketball this would be called “drawing the foul,” where one deliberately places oneself in a position so that the opposing player cannot avoid initiating an illegal contact, thus conceding a penalty. How can it be fair, or even strategically prudent, to allow ourselves to be neutered in such a way by upholding the rules when our enemy does not?

The answer is actually very straightforward. The fact that “we” are supposed to be bound by the rule of law and the values that underpin it demonstrates precisely why “we” are supposed to be better than them and why “we” deserve to win. The fact that “they” are not held to the same legal and ethical stan­dards is not an excuse for watering down our standard of justice or hiding behind legal technicalities. The simple response is that it does not matter if our opponents ignore or flout the rules. Those rules, and the values they represent, are part of our identity – and this identity is a strength, not a weakness. We only harm ourselves if we try and leave them behind or get around them somehow. As well as it being the right thing to do, there are sound strategic reasons for maintaining the ethical traditions that govern the military profession, not least for maintaining professional identity and a sense of common purpose. For the professional soldiers I have had the privilege to work with over the last decade, I know that, for them, how one fights is at least as important as what one fights for.

1 A substantially expanded version of this argument will appear in The Monist (2015): vol. 98, issue 4.

2 Glenn, Russell W. (2009): “Thoughts on ‘Hybrid’ Conflict,” Small Wars Journal, March.

3 Lucas, G. R. (2015): Military Ethics: What Everyone Needs to Know, Oxford, p.4.

4 For a fuller exposition of this argument, see Whetham, D. and Lucas, G. R. (2015): “The Relevance of the Just War Tradition to Cyber Warfare,” in: Green, James A. (ed.), Cyber Warfare: A Multidisciplinary Analysis, Abingdon and New York.



Dr. David Whetham is Reader in Military Ethics in the Defense Studies Department of King’s College London. He is Director of the King’s Centre for Military Ethics and delivers or coordinates the military ethics component of courses for 2,000 to 3,000 British and international officers a year at the UK’s Joint Services Command and Staff College. He has held visiting fellowships at the Stockdale Center for Ethical Leadership, Annapolis, the Centre for Defence Leadership and Ethics at the Australian Defence College in Canberra, and at the University of Glasgow. He is also a regular visiting lecturer at the Baltic Defence College, the Military Academy in Belgrade, and for the Royal Brunei Armed Forces. Publications include Ethics, Law and Military Operations (2010), Just Wars and Moral Victories (2009), and together with Andrea Ellner and Paul Robinson (eds), When Soldiers Say No: Selective Conscientious Objection in the Modern Military (Ashgate, 2014). He is also the Vice President of the European Chapter of the International Society for Military Ethics (Euro ISME).