The nature of war has undergone a profound change over the course of history, particularly during the twentieth century. Power conflicts, pitting the armies of developed states against one another, have all but disappeared with the setting up of a legal framework limiting governments’ recourse to force to resolve their differences. This has not prevented military expenditure from increasing, nor has it stopped the major powers from intervening in local conflicts. This development goes hand in hand with a tendency to privatize war, and the emergence of companies providing mercenaries is one of its most spectacular symptoms.

War is an armed conflict between social groups, taking place over a time period and with a political objective: resolving a dispute (ideological, religious, etc.), conquering a territory, appropriating resources, etc. In the line of thinking inherited from Clausewitz (19th century), war is the paroxysmal but natural culmination of rivalries between states ; it arises from the normal interplay of relations between states because no supranational authority can limit one state’s sovereign decision to use force to safeguard its interests. Peace, negatively defined as the absence of war, is merely an exceptional state of affairs.

This Eurocentric understanding of war, perceived as a clash between inevitably rival powers, has lost relevance in today’s world due to the way military capabilities have evolved and the regulation of warfare by collective institutions and international law. While wars themselves have not disappeared, those arising exclusively from a confrontation between national armies are rare.

War’s legal framework

Rules to regulate the conduct of warfare have existed since antiquity (Olympic truce, etc.), yet it was not until the 16th century that the concept of a just war emerged in Europe, developed in particular by the School of Salamanca and Hugo Grotius. Drawing on Thomas Aquinas (13th century), they established the foundations of international law, i.e. the rules governing reasons for declaring war (jus ad bellum) and its conduct (jus in bello), including the principle of proportionality in the use of force, respect for civilians (thus making a distinction between civilians and military personnel), etc. Initially a matter of convention, the rules governing warfare were progressively codified in international treaties. After the Hague Conventions of 1899 and 1907 were swept away by the First World War, various texts and treaties (including the Geneva Conventions of 1949 and their Additional Protocols) established the current foundations of international humanitarian law protecting civilians and prisoners, forbidding the use of torture, prohibiting certain types of weapons (biological weapons in 1972, chemical weapons in 1993, cluster munitions in 2008, etc.) or specific practices (enrolment of child-soldiers in 1989, etc.).

Institutions were set up in parallel which, while not actually preventing wars, tend to render them illegitimate. Since the Congress of Vienna (1815) the great powers have been agreed on needing to limit the right to resort to war. Then the First World War acted as a catalyst: condemned by public opinion, and depicted as a moral and civilizational breakdown, it led to the creation of the League of Nations and then, after the Second World War, to that of the United Nations Organization, charged with maintaining peace and security. Now the practice of war is justified only by self-defense or by collective decisions (via the Security Council) in cases where peace is endangered. The almost universal disapproval of the coalition led by the United States in Iraq in 2003, without a UN mandate, illustrates this key development over time: in order to be legitimate, the use of force requires endorsement by the international community.

Increasingly sophisticated weapons

Even as inter-state wars have become rare, paradoxically, state military budgets have been steadily increasing, especially among emerging countries and regional powers. China’s military budget has increased ten-fold since 1998, creating a security dilemma situation that in turn prompts significant increases among its neighbors (Vietnam, etc.). A similar trend is apparent in the Persian Gulf, and in Saudi Arabia in particular, where arms purchases from the great powers serve both to bolster states’ military capabilities and to enhance their influence and serve diplomatic ends. Because if states no longer engage in war directly, they continue to intervene in peripheral conflicts, even though they have less and less control over the consequences of doing so (Afghanistan, Syria, Iraq, Yemen, Mali, etc.).

This surge in military expenditure is also driven by the growing sophistication of weapons systems. Given public opinion’s rejection of war, the aim of the major powers, going forward, is that weapons development by the military-industrial complex should enable them to avoid losses in their own ranks (zero casualty doctrine). For centuries, military technology saw little change and the key factor in victory was the number of men mobilized. The arrival of gunpowder in the 15th century, and above all the growth of aviation in the 20th century, were game-changing developments, permitting bombardments on a massive scale (including nuclear bombardments in 1945). The development of ballistic missiles and more recently of drones completed this military revolution: now conflict participants can avoid exposure and personnel numbers are relatively insignificant. The deployment of armed robots, capable of deciding to kill autonomously, is currently giving rise to unprecedented ethical debate.

Military drones, 2017

Sources: The Bureau of Investigative Journalism,; New America (World of Drones Database); UAV Global,

Comment: The United States is the main user of military drones to carry out bombings. Since 2001, there have been many American attacks on Afghanistan, despite the lack of information, but Pakistan, the Yemen and Somalia have suffered bombings (graph) as well. Because governments are opaque about these types of attack, consortiums of journalists report the victims of these strikes from a distance. Countries that possess these devices are known thanks to observers of this high-tech industry (map).

Toward a privatization of violence?

This trend goes hand in hand with the rise of mercenary operators (euphemistically known as Private Military Companies – PMCs), used by governments (Western and Russian governments in particular) to intervene in conflicts without being directly exposed to them. Offering a broad range of services (from security to heavy weapons combat), they are tending to privatize security, transforming war into a commercial activity while profiting from the legal uncertainty within which they operate, outside the scope of the international treaties which define combatants’ obligations. A chasm is opening between the wealthy, over-armed North which is safeguarding its own population to the extent of delegating war to private armies, and the South where widespread violence seems to be devaluing individual lives.

Victims of armed groups, 1989-2016

Source: UCDP Georeferenced Event Dataset Codebook Version 17.1, Department of Peace and Conflict Research, Uppsala University,

Comment: The Uppsala Conflict Data Program compiles a register of “events” – that is cases of violence leading to death – from multiple sources. These estimates can sometimes be lower than they are in reality, since not all cases are reported. The circles on the map show the number of deaths since 1989 on the basis of a 100x100 km grid. The deadliest areas are found in Africa (the central strip in particular), the Middle East and Afghanistan/Pakistan. Other violent areas also appear, with fewer or more localized total numbers: Colombia, Peru and Mexico, the Philippines, Sri Lanka and the Indian subcontinent, Yemen, the Caucasus and the Balkans.

Victims of armed groups, 1989-2016

Source: UCDP Georeferenced Event Dataset Codebook Version 17.1, Department of Peace and Conflict Research, Uppsala University,

Comment: The Uppsala Conflict Data Program compiles a register of “events” – that is, cases of violence leading to death – from multiple sources. These estimates can sometimes be lower than they are in reality, since not all cases are reported. The graphs show the chronology of numbers killed in states where more than 10,000 deaths have been recorded since 1989. The scale of the Rwandan genocide (1994) is striking. Some states display numerous deaths throughout the period (Sudan, Somalia, India, Afghanistan); other conflicts seem, in principle, to be resolved (Angola, Bosnia, etc.), while yet others are more recent (Nigeria, Yemen and Syria).

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