Humanitarian intervention is the use or threat of military force by a state (or states) across borders with the intent of ending severe and widespread human rights violations in a state which has not given permission for the use of force. Humanitarian interventions are aimed at ending human rights violations of individuals other than the citizens of the intervening state. Attempts to establish institutions and political systems to achieve positive outcomes in the medium- to long-run, such as peacekeeping, peace-building and development aid, do not fall under this definition of a humanitarian intervention.

There is not one standard or legal definition of humanitarian intervention.Jennifer M. Welsh. Humanitarian Intervention and International Relations. Ed. Jennifer M. Welsh. New York: Oxford University Press, 2004. Nonetheless, there is a general consensus on some of its essential characteristics:Alton Frye. 'Humanitarian Intervention: Crafting a Workable Doctrine.' New York: Council on Foreign Relations, 2000. Humanitarian intervention involves the threat and use of military forces as a central feature. It is an intervention in the sense that it entails interfering in the internal affairs of a state by sending military forces into the territory or airspace of a sovereign state that has not committed an act of aggression against another state. The intervention is in response to situations that do not necessarily pose direct threats to states' strategic interests, but instead is motivated by humanitarian objectives.

The customary international law concept of humanitarian intervention dates back to Hugo Grotius and the European politics in the 17th century.Eaton, Jonah (2011). An Emerging Norm - Determining the Meaningand Legal Status of the Responsibility to Protect. (Michigan Journal of International Law vol. 32, iss. 4 (2010-2011), p. 765-804). “The idea of sovereignty as an instrument for the protection of the life and safety of subjects is at least as old as Hugo Grotius, who made "the first authoritative statement of the principle of humanitarian intervention - the principle that exclusiveness of domestic jurisdiction stops when outrage upon humanity begins."” However, that customary law has been superseded by the UN Charter, which prohibits the use of force in international relations, subject to two exhaustive exceptions: UN Security Council action taken under Chapter VII, and self-defence against an armed attack. The type and frequency of humanitarian interventions have changed drastically since the 19th century, with a massive increase in humanitarian interventions since the end of the Cold War. Historically, humanitarian interventions were limited to rescuing one's own citizens in other states or to rescue ethnically or religiously similar groups (e.g. Christian countries intervening on behalf of Christians in non-Christian countries). Over the course of the 20th century (in particular after the end of the Cold War), subjects perceived worthy of humanitarian intervention expanded beyond religiously and ethnically similar groups to encompass all peoples.

The subject of humanitarian intervention highlights the tension between the principle of state sovereignty – a defining pillar of the UN system and international law – and evolving international norms related to human rights and the use of force.Shashi Tharoor and Sam Daws. "Humanitarian Intervention: Getting Past the Reefs." World Policy Journal 2001. The legal justification for humanitarian interventions without the authorization of the UN Security Council remains extremely controversial. There are normative and empirical debates over its legality, the ethics of using military force to respond to human rights violations, when it should occur, who should intervene,James Pattison, Humanitarian Intervention and the Responsibility to Protect: Who Should Intervene? Oxford: Oxford University Press, 2010. and whether it is effective. Its frequent use following the end of the Cold War suggested to many that a new norm of military humanitarian intervention was emerging in international politics.

History The notion of humanitarian interventions, understood as interventions in other states to stop human rights abuses, has been observed since the 19th century. Scholars have often identified the interventions in the Greek War of Independence (1821-1829) as the first humanitarian intervention. Humanitarian concern was apparent when Britain, France and Russia decisively intervened in a naval engagement at Navarino in 1827 to secure for the Greeks independence from the Ottoman Empire. Popular opinion in England was sympathetic to the Greeks (philhellenism), in part due to the Greek origin of the West's classical heritage. The renowned poet Lord Byron even took up arms to join the Greek revolutionaries, while the London Philhellenic Committee was established to aid the Greek insurgents financially.

In 1823, after initial ambivalence, the Foreign Secretary George Canning declared that "when a whole nation revolts against its conqueror, the nation cannot be considered as piratical but as a nation in a state of war". In February that same year, he notified the Ottoman Empire that the United Kingdom would maintain friendly relations with the Turks only under the condition that the latter respected the Christian subjects of the Empire. He was also instrumental in the outcome of the St. Petersburg Protocol 1826, in which Russia and Britain agreed to mediate between the Ottomans and the Greeks on the basis of complete autonomy of Greece under Turkish sovereignty.Stavrianos, The Balkans since 1453, pp. 288–289. When this did not end the War, Canning negotiated a following treaty that ultimately led to the destruction of the Egyptian-Turkish fleet at the Battle of Navarino.

The treatment of minorities under the Ottoman aegis proved a rich source of liberal agitation throughout the nineteenth century. A multinational force under French leadership was sent to Lebanon to help restore peace after the 1860 Druze–Maronite conflict, in which thousands of Christian Maronites had been massacred by the Druze population. Following an international outcry, the Ottoman Empire agreed on 3 August 1860 to the dispatch of up to 12,000 European soldiers to reestablish order.Just war or just peace?: humanitarian intervention and international law by Simón Chesterman p.32ff. This agreement was further formalized in a convention on 5 September 1860 with Austria, Great Britain, France, Prussia and Russia.

In May 1876 Ottoman troops began massacring unarmed agitators for autonomy in Bulgaria, leading to the Eastern Crisis. The British launched a government investigation into the events, which confirmed that as part of an official policy, the Turks had killed at least 12,000 Bulgarians and obliterated about 60 villages. Lurid reports began to appear in newspapers, especially accounts by the investigative journalist William Thomas Stead in the Northern Echo, and protest meetings were called across the country.

Despite the unprecedented demonstration of the strength of public opinion and the media, the Prime Minister Benjamin Disraeli remained an unmoved practitioner of realpolitik, and considered British interests to lie in the preservation of Ottoman sovereignty in Eastern Europe. Lord Derby the Foreign Secretary disagreed and telegraphed the Sublime Porte that "any renewal of the outrages would be more fatal to the Porte than the loss of a battle." Apart from issuing stern advice and proposals for internal Turkish reform and the legal protection of minorities, the Disraeli government did nothing. However, the issue convulsed British politics with former Prime Minister William Ewart Gladstone coming out of retirement to campaign over the atrocities. In a famous campaigning speech he said: Let the Turks now carry away their abuses, in the only possible manner, namely, by carrying off themselves. Their Zaptiehs and their Mudirs, their Blmhashis and Yuzbashis, their Kaimakams and their Pashas, one and all, bag and baggage, shall, I hope, clear out from the province that they have desolated and profaned. This thorough riddance, this most blessed deliverance, is the only reparation we can make to those heaps and heaps of dead, the violated purity alike of matron and of maiden and of child; to the civilization which has been affronted and shamed; to the laws of God, or, if you like, of Allah; to the moral sense of mankind at large.

Rising Great Power tensions in the early 20th century and the interwar period led to a breakdown in the concerted will of the international community to enforce considerations of a humanitarian nature. Attempts were made under the auspices of the League of Nations to arbitrate and settle international disputes. Aggressive actions, such as the Italian Invasion of Abyssinia and the Japanese occupation of Manchuria were condemned, but the League lacked the resolve to enforce its will effectively. The Allied discovery of the Holocaust and the subsequent Nuremberg trials at the end of World War II caused attitudes to change considerably. After the tragedies in Rwanda and the Balkans in the 1990s, the international community began to debate how to react to cases in which human rights are grossly and systematically violated. Especially, in his Millennium Report of 2000, then Secretary-General of the United Nations Kofi Annan, called on Member States: "If humanitarian intervention is indeed an unacceptable assault on sovereignty, how should we respond to a Rwanda, to a Srebrenica, to gross and systematic violations of human rights that offend every precept of our common humanity?". Since the end of the Cold War, interventions have increasingly been used, such as the NATO bombing of Yugoslavia and the 2011 military intervention in Libya.

Philosophy of humanitarian intervention

One of the first champions of the duty of humanitarian intervention to prevent atrocities around the world, was the Victorian liberal John Stuart Mill, who wrote in his 1859 essay A Few Words on Non-Intervention:John Stuart Mill (1859) A Few Words on Non-Intervention at the Online Library of Liberty

"There seems to be no little need that the whole doctrine of non-interference with foreign nations should be reconsidered, if it can be said to have as yet been considered as a really moral question at all... To go to war for an idea, if the war is aggressive, not defensive, is as criminal as to go to war for territory or revenue; for it is as little justifiable to force our ideas on other people, as to compel them to submit to our will in any other respect. But there assuredly are cases in which it is allowable to go to war, without having been ourselves attacked, or threatened with attack; and it is very important that nations should make up their minds in time, as to what these cases are... To suppose that the same international customs, and the same rules of international morality, can obtain between one civilized nation and another, and between civilized nations and barbarians, is a grave error...."

In 1859, Mill wrote that both Algeria and India (both of which were under European colonial rule) were inhabited by "barbarous peoples". Mill's justification of intervention was overt imperialism. First, he argued that with "barbarians" there is no hope for "reciprocity", an international fundamental. Second, barbarians are apt to benefit from civilized interveners, said Mill, citing Roman conquests of Gaul, Spain, Numidia and Dacia. Barbarians,

"have no rights as a nation, except a right to such treatment as may, at the earliest possible period, fit them for becoming one. The only moral laws for the relation between a civilized and a barbarous government, are the universal rules of morality between man and man."