The nature of warfare has been perpetually altered by continuous innovation in technology and strategy throughout history, never remaining static for long periods of time. This rate of change, however, vastly accelerated during the 20th century seeing a change from cavalry and bayonet charges through nuclear weapons to stand-off precision weapons and cyber warfare. This article will explore some of the key foundational concepts of 21st-century warfare and provide a concrete set of definitions on which this series will base its analysis. It will then explore the scope and range of topics that will be covered in the series going forward and provide a brief overview of Ukraine in order to ground these topics in a conflict currently taking place.

Some definitions

To set the conditions for a comprehensive analysis of these changes, it is first necessary to provide some concrete definitions for often misunderstood or misused terms relating to the topics of irregular warfare and warfighting. 

Warfighting

Warfighting, as the name would suggest, refers to the action of fighting a war, specifically and crucially this conflict is through kinetic means with physical military engagement between belligerents. The UK Ministry of Defence states “while the character of warfare is changing, the nature of war does not change, it is always about the violent interaction between people.” This highlights the key point in this term that warfighting is not conflict or contest between groups but rather, actual direct military action. The term ‘conventional warfighting’ will also be used throughout this series to refer to so-called “peer” and “near-peer” warfighting, i.e. warfighting against an adversary considered to be militarily equal or near-equal in terms of capability. A traditional example of this would be, from a US perspective, China as a peer adversary or Iran as a near-peer adversary.

Hybrid Warfare

Hybrid warfare is not a doctrinally defined term within a Western military context, rather it is a concept developed by Frank Hoffman to describe the emerging threat of multifaceted military entities in 21st-century conflict. He talks specifically about the blend between conventional warfighting, irregular warfare,  and terrorism or organised crime. Specifically, he describes hybrid warfare as being conducted by state or non-state actors and involving an ambiguous mix of combatants and tactics to exploit military vulnerabilities in a force. While he uses the example of Hezbollah in 2006, a more current example would be the Russian forces deployed in Ukraine where a large conventional Russian Armed Forces (RuAF) element is augmented by militia forces from the Luhansk and Donetsk People’s Republics (LPR and DPR as well as mercenaries from the Wagner Group amongst others). The term hybrid warfare is often deployed in a context of national competition below the threshold of conflict such as economic warfare, energy warfare or political interference. This is beyond the scope of both Hoffman’s definition as well as the range of this article series and as such we will focus on the, primarily, military nature of Hoffman’s definition. 

This form of conflict is becoming increasingly common as states seek to conduct military operations without the domestic and political risk of their state military involvement. These militias offer a level of deniability along with leveraging existing local disputes, power structures and sentiments to increase the chance of military success. Another current example would be that of the ongoing conflict in Syria where various militia factions are supported to varying degrees by the West, Turkey, Iran and the Syrian government itself with international state involvement including the US, Russia and the UK supporting these factions with air-strikes and troops on the ground. It is difficult today to find or imagine an active conflict that does not correspond to this definition. On the contrary, it has become an essential element in conduct of warfare, as irregular forces are often capable combatants and can cause difficulties for conventional military forces.

Irregular Warfare

Irregular warfare has traditionally been used, incorrectly, to describe all military activity that does not fit within the traditional view of conventional warfighting. The Modern War Institute defines it as “a coercive struggle that erodes or builds legitimacy for the purpose of political power. It blends disparate lines of effort to create an integrated attack on societies and their political institutions. It weaponizes frames and narratives to affect credibility and resolve, and it exploits societal vulnerabilities to fuel political change. As such, states engaged in or confronted with, irregular warfare must bring all elements of power to bear under their national political leadership.” The key point is that this form of warfare involves various techniques and groups that are not considered conventional and can, but does not necessarily have to, involve violent conflict. Examples of techniques that could be considered irregular warfare would be the spreading of disinformation to reduce legitimacy of a military group. An example could be the Russian focus on and inflation of the far-right elements of the Ukrainian military to portray the entirety of Ukraine as a far-right state despite that not being the case overall.

Asymmetric Warfare

Asymmetric warfare has a simple definition but two completely different military situations in which this definition can be applied. Kenneth McKenzie Jr defines it as “leveraging inferior tactical or operational strength against [the] vulnerabilities of a superior opponent to achieve disproportionate effect.” While this in itself is a fairly tangible definition, the nuances of this term are in what is being considered asymmetric. For example, a war between a nuclear and non-nuclear state could be considered asymmetric even if the belligerents were equal in conventional military power. Similarly, any war involving the US could be considered asymmetric given the unmatched scale of the US Air Force (USAF). 

For this series, asymmetry will be used in three ways. Firstly, strategic asymmetry. This concept can be used to describe warfare between two fundamentally unequal military groups where one side is totally outmatched in every metric. An example of this would be the conflict between the International Security Assistance Force (ISAF) and the Taliban within Afghanistan where ISAF outmatched the Taliban in technology, funding, manpower, training and equipment. It is important to note here that strategic asymmetry does not guarantee defeat for the weaker side as this example illustrates.

A second use of the term asymmetric warfare is that of operational or tactical asymmetry. This can be broken down into asymmetry in tactics, techniques and procedures (TTPs) and asymmetry in physical metrics such as equipment or manpower figures. Asymmetric TTPs can be used to describe the situation in which belligerents with a level of conventional military equity seek gains by changing tactics to exploit a perceived weakness. For example, the Ukrainian Kharkiv counteroffensive exploited a perceived stretching of weakened Russian defensive lines by massing lightly armed vehicles with high operational mobility to penetrate and exploit the Russian lines achieving rapid victories. This tactic would not be found in any Soviet, Russian or Ukrainian doctrine handbook and instead capitalised on the available equipment and condition of the battlefield to defeat an opponent expecting a conventional attack.

Further, asymmetry can be used to refer to a disadvantage or difference in a specific physical measurement of military power. This could include a disadvantage in the numbers of troops, equipment or ammunition such as the artillery barrel and ammunition deficit that left Ukraine facing a 10:1 disadvantage around Bakhmut or a specific capability gap such as Ukraine’s lack of a blue water navy or any navy at all. These asymmetric disadvantages leave room for asymmetric innovations and technologies to fill, many of which will be explored in this series. 

Unconventional Warfare

Unconventional warfare refers specifically to activities designed to support an insurgency or resistance group in order to achieve political and military goals. It is an element of irregular warfare.

Grey Zone Warfare

Another poorly doctrinally defined yet widely used term. Grey zone warfare has been explained by the Australian government as “activities designed to coerce countries in ways that seek to avoid military conflict... paramilitary forces, militarisation of disputed features, exploiting influence, interference operations and the coercive use of trade and economic levers.” This essentially overlaps with the definition of irregular warfare but refers more to the non-physical domain in which this activity occurs; the ‘grey zone’. A key point here being that this definition is self-contradictory, stating that grey zone warfare seeks to avoid military conflict but advocates militarisation and interference operations as acceptable tactics. The point this definition is trying to get at is that grey zone warfare seeks to avoid conventional military conflict. The Nord Stream bombings were almost certainly a military operation of some kind regardless of speculation of actors involved, however this activity was designed to add a layer of deniability in order to get a state-on-state advantage without escalating to conventional war.

There is significant overlap between these definitions, some of which are based on existing military doctrine and others which have been created as theoretical tools to group together certain types of military activity. 

The diagram below is intended to visually illustrate the overlap of some of these terms and theories and to show how various military actions can be categorised into a certain form of warfare.

Scope of this series

This series will explore a variety of TTPs, technological innovations, and changes in military force design that have occurred or may occur in the near term at tactical, operational, and strategic levels. It will illustrate how the changing nature of conflict has influenced and will continue to influence military development in technology, equipment and TTP in the future. The focus will be on the military aspect of these changes rather than the political aspects covered in the Hybrid Warfare series. The series will largely explore topics relating to the Russian invasion of Ukraine, as it is the most recent crucible in which these changes can be observed and from which these innovations have, are and will emerge. These lessons and observations can then be applied to other regions of the world to examine their impact on warfighting in the 21st century more generally. 

Ukraine as a case study for irregular warfare

The Ukrainian conflict is an ideal case study for examining the various forms of warfare defined above and the physical manifestations of these forms of conflict. 

The Ukrainian conflict encompasses all the forms of warfare that this series seeks to cover, from targeted assassinations in Moscow to the destruction of critical national infrastructure and the development of improvised or homemade naval and unmanned aerial systems. While it is not the intention of this series to focus entirely on Ukraine, the conflict provides the most recent evidence base from which lessons can be learned and developments in technology and TTP can be observed. Moreover, the war in Ukraine has provided perhaps the first example of real warfare in the 21st century and has proved to be a theoretical watershed moment as traditional post-Global War on Terror Western thinking sought to distance itself from conventional warfare in Europe and focus on irregular warfare in the Indo-Pacific, as the Integrated Review illustrates. The Russian invasion brought an interesting change to this view, forcing Western states, while not discounting the rising threat posed by China, to accept that the idea of interstate conflict in Europe is not as distant as once thought.

At an operational level, the war in Ukraine has proved another assertion about 21st-century conflict wrong. The idea that conventional warfare is still relevant was relegated to the background in favour of expeditionary, asymmetric, and interventionist warfare as demonstrated in Iraq, Afghanistan, Libya, Mali, and South Sudan among others. What Ukraine has shown is that while conventional warfare is still of crucial importance, its nature has entirely changed, as we will see in other articles. 2,000 destroyed, damaged or abandoned Russian tanks would seem to suggest that the TTPs, technology or equipment that the Russian Armed Forces (RuAF) have employed so far are fundamentally challenged in the conventional warfighting environment of the 21st century and that there are many lessons to be drawn from their actions, failures, and successes.

The conflict has also provided numerous opportunities to observe asymmetric warfare in action, with examples such as the use of custom-built unmanned surface vessels (USVs) by the Ukrainian army to challenge the Russian Black Sea Fleet or the procurement and employment of Western air defence systems to counter the threat posed by the Russian Air Force and Russian long-range precision guided munitions (LR-PGMs) such as Kalibr, Kinzhal or Iskander-M missiles. This asymmetric tool employed by Ukraine has denied Russian forces air superiority, a key tool that facilitated the allied success in Desert Storm.

Conclusion

In conclusion, this brief introduction to the terms and primary case studies to be used throughout this series aims to have provided a basic conceptual understanding of the spheres of conflict that sit below and alongside the conventional understanding of warfighting. Going forward the series will explore a variety of domains and specific examples of technologies and strategies that exist within these spheres and the impact that these will have on warfighting and conflict in general going forward. These examples will be explored at a variety of scales with innovations at the strategic, operational and tactical levels as well as exploring entirely new domains of conflict such as deep sea warfare.

As the conflict in Ukraine is currently demonstrating, irregular and unconventional warfare is likely to become more prevalent in the coming decades even as conventional interstate conflict continues as a major security threat. As the conflict continues, new material and tactical developments continue to appear driven by the combination of limited economic and military resources on both sides as well as the push to achieve a military advantage and improve the situation on the battlefield.

These developments in Ukraine are being watched globally by various militaries to form the basis for new policy, procurement decisions, and military innovations to move from the traditional Cold War model of interstate warfare to the hybrid forms seen today. The successes and failures of these developments, and their applicability to other potential and current theatres of conflict, will pave the way and shape the nature of 21st-century warfare.