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The concept of collective security replaces the one of military alliances between States, which prevailed until World War II, to ensure the collective defense of a State by its allies in case of aggression by another State. Collective security refers to a system put in place by the United Nations Charter in 1945. Other mechanisms of collective security exist at the regional level.
The UN Charter governs this system for the entire international community. This system creates international mechanisms of pacific settlement of disputes between States. In case this system fails or in case of threat to international peace and security caused by the behavior of one or several States, the United Nations Security Council is competent to use international armed force to manage this threat. In counterpart to this mechanism, the Charter prohibits the unilateral use of force in the relations between States. The only exception provided by the Charter concern cases of self-defense (Art. 51 of the Charter). The term “collective security” is based on the need to defend the international public order. This definition, partially contained in the UN Charter, has been continuously interpreted by the UN Security Council.
One of the primary objectives of the UN is to “maintain international peace and security, and to that end: to take effective collective measures for the prevention and removal of threats . . . or breaches of the peace” (Art. 1 of the UN Charter). With this consideration, the UN system of collective security includes mechanisms for the pacific settlement of disputes—using arbitration and conciliation—as well as options for international peacekeeping or peacemaking action.
The system prohibits States from using or threatening to use force in their interstate relations, except in cases of self-defense (Arts. 2.4, 51). However, the Charter establishes a two-step method for collective response, and it entrusts the Security Council with the principal responsibility for it (Art. 24):
- Step 1: Pacific Settlement of Disputes (Chapter VI of UN Charter). In the initial phase, the Council must strive to facilitate the pacific settlement of disputes among the concerned States. This is the preventive stage. States are under the obligation to seek peaceful solutions to their disputes, whether through negotiation, inquiry, mediation, conciliation, or arbitration (Art. 33). However, the Security Council may expressly call on the parties to do so, if it deems it necessary. It may also investigate any dispute to determine whether its continuation threatens international peace and security (Art. 34). In any case and at any stage in the dispute, the Council may recommend procedures or methods of adjustment that it considers appropriate. In particular, it may suggest that States refer legal disputes to the International Court of Justice (Art. 36).
If the perpetuation of the dispute is likely to endanger international peace and security, States are under the obligation to submit their disputes to the Security Council. The Council may also consider a case and make recommendations if all States party to the dispute request it. Normally, it is not possible for a State to resort to force while using the pretext of an unresolved dispute, if the UN Security Council was not consulted on the matter first. The International Court of Justice specified that only acts of aggression could authorize the recourse to legitimate self-defense. On the contrary, the other types of threats to international security cannot justify recourse to armed force and must be brought before the UN Security Council. The jurisprudence of the International Criminal Court has also clarified the definition of aggression. This definition was integrated in 2010 in the Statute of the ICC.
- Step 2: Responses to Breaches of the Peace and Acts of Aggression (Chapter VII of UN Charter). In cases of threats to the peace, breaches of the peace, and acts of aggression, if all preventive actions fail, the Security Council may have recourse to more forceful measures such as sanctions, including military ones. It is up to the Council to determine the existence of a “threat to international peace and security.” It examines each situation referred to it individually and decides whether the public international order is in danger. The reasons set forth by the Council vary from one situation to another. In particular, the Council may decide to adopt provisional measures that are without prejudice to the rights of the parties concerned (Art. 40). These measures are binding on all States. To ensure that its decisions are respected, the Council may apply various kinds of diplomatic or economic sanctions. Should it consider that such measures have proven inadequate, it may eventually employ international armed forces to restore order. Although paralyzed during the Cold War, the UN Security Council has authorized the use of international armed force on several occasions since the beginning of the nineties. When authorizing military interventions, the Security Council issued resolutions insisting that grave violations of human rights may constitute a threat to international peace and security (Resolution 688  on Iraq; Resolution 941  on Bosnia; Resolution 955  on Rwanda; Resolution 1203  on Kosovo). The Security Council expressed its strong condemnation of all forms of violence against humanitarian personnel and requested the Secretary-General to address issues of the safety and security of humanitarian and United Nations and associated personnel in all his country-specific situation reports (S/RES/1502 ). This resolution was preceded by numerous reports from the Secretary-General on the protection of civilians and Security Council resolutions: S/RES/1265 (1999); S/RES/1296 (2000); Report of the Secretary-General to the Security Council on the Protection of Civilians in Armed Conflict, S/2008/643, 28 October 2007; S/2009/277, 29 May 2009; S/2010/579, 11 November 2010. However, even if the UN Security Council adopted Resolution 1674 in 2006 relative to the responsibility to protect civilian populations in danger, this does not mean that there now exists an international right or duty to intervene where human rights and humanitarian law are seriously violated. Human rights and humanitarian law violations have become a matter of international public order but they are not sufficient to qualify a situation as a threat to peace or international security as this depends on political consensus at the UN Security Council level. At best, these elements may add to other elements reaching the threshold of a threat to or breach of international peace and security. The Security Council is often blocked by veto and refrained to act in a situation that involves one of its permanent members.
Within the framework of its mandate to protect international peace and security, the Security Council, acting under Chapter VII of the UN Charter, has also imposed upon States the jurisdiction of International Criminal Tribunals in charge of prosecuting those responsible for war crimes, crimes against humanity, and genocide committed on the territory of these States. For example, the Security Council created the ad hoc International Criminal Tribunals for the former Yugoslavia and for Rwanda. In 2005, the Security Council referred the situation in Darfur (Sudan) to the prosecutor of the International Criminal Court (Resolution S/RES/1593/2005). The vote of the Resolution of the Security Council gave the ICC jurisdiction over a State that has not yet ratified the Rome Statute.
In 2011, the Security Council imposed the jurisdiction of the ICC on Libya by adopting Resolution 1970 based on Chapter VII of the Charter (S/RES/1970/2011). Concerning the situation in Syria since 2011, the Council did not reach a consensus, neither on a potential military intervention nor on referral to the ICC.
In determining whether a threat or breach of the peace exists, the Security Council examines various criteria. Since those on which it bases its final decisions—further influenced by the possible veto of the permanent members of the Council—vary from case to case, it is very difficult, in practice, to determine what situation might trigger that reaction.
Other systems of collective security exist at the regional level, especially in Europe. They often function according to principles similar to those set by the UN, and in any case they have the duty to respect the global system. The Security Council may subcontract missions to regional organizations responsible for these regional mechanisms (e.g., NATO, OSCE, WEU, OAU), in accordance with Chapter VIII of the UN Charter. However, in such cases, the Council remains responsible for monitoring—and therefore retains the authority over—the use of force carried out on its behalf (Arts. 53, 54).
Debate on the reasons for supporting international interventions continues within the United Nations. Meanwhile, the Constitutive Act of the African Union (AU), adopted in 2000 at the Lomé summit, broadened the legal basis of the international right to intervene within the States of the Union. Article 4 of the Act recognizes the right of the Union to intervene in a Member State’s affairs pursuant to a decision of the Assembly in respect of grave circumstances, namely, war crimes, genocide, and crimes against humanity. This is a new step for the African Union. However, the lack of financial, technical, and logistical means in several African States emphasizes the fact that, in this region, States will continue to depend on external support, particularly from the United States and the European Union.
▸ African Union ▸ Aggression ▸ International Court of Justice ▸ International Criminal Court ▸ International Criminal Tribunals for the Former Yugoslavia (ICTY) and Rwanda (ICTR) ▸ Intervention ▸ Peacekeeping ▸ Public order ▸ Sanctions (diplomatic, economic, or military) ▸ Security Council of the UN ▸ Self-defense ▸ United Nations
For Additional Information: Abass, Ademola. Regional Organisations and Development of Collective Security: Beyond Chapter VIII of the UN Charter . Portland, OR: Hart Publishing, 2004.
Koskenniemi, Martti. “The Place of Law in Collective Security.” Michigan Journal of International Law 17 (1996): 455.
Roberts, Adam, and Benedict Kingsbury, eds. United Nations, Divided World: The UN’s Roles in International Relations . New York: Oxford University Press, 1993, esp. 63–103.
Weiss, Thomas G., David P. Forsythe, and Roger A. Coate. The United Nations and Changing World Politics . Boulder, CO: Westview, 1997, esp. 21–122.
Weissman, Fabrice. In the Shadow of “Just Wars”: Violence, Politics and Humanitarian Action . London: Hurst, 2004.
White, Nigel D., ed. Collective Security Law . Aldershot, UK: Ashgate, 2003.