The idea that all states should respect a common and binding set of rules defining the outbreak and conduct of war gradually gained ground during the 19^th century. It was based on the principles of sovereign equality of states, territorial integrity, self-determination, and non-interference in internal affairs. It was hoped that international law would govern the behaviour of states in order to prevent the application of the law of the strongest.

The Geneva Convention of 1864, established at the initiative of the Inter- national Committee of the Red Cross (ICRC), constituted the first treaty aimed at improving the living conditions of soldiers wounded in armed conflicts by establishing rules relating to their care and protection. They marked the beginning of international humanitarian law. In 1888, Luxembourg also acceded to the Geneva Convention. The Luxembourg Red Cross was founded on 6 August 1914, shortly after the start of the First World War.

Another pivotal moment was the organisation of the two international peace conferences in The Hague in 1899 and 1907. They emphasised the importance of arbitration for conflict resolution and, for the first time, the necessity of disarmament. The Luxembourg delegation actively participated in the 1907 deliberations on codifying the rights and obligations of neutral states in times of war as well as peace.

The first Hague Conference also established the Permanent Court of Arbitration, the first international judicial institution. Its objective was to resolve disputes between states by submitting them to a neutral arbitrator rather than settling them on the battlefield. Since 1946, the International Court of Justice (ICJ) adjudicates legal disputes between states and issues advisory opinions on international law. On the other hand, the International Criminal Court (ICC), established in 2002, prosecutes individuals for serious crimes such as genocide and war crimes. Finally, special war crimes tribunals were created starting in the 1990s, notably in the conflicts in Yugoslavia and Rwanda.

Founded in 1920, the League of Nations (LON) was the first permanent international organisation dedicated to preserving peace and collective security. It was established after the First World War by the Treaty of Versailles to make the Great War “the war to end all wars”.

The LON was conceived as a forum for open diplomacy and facilitated solidarity and collaboration among nations in the commercial, intellectual, social, and political spheres. It championed, among other things, the territorial integrity of nations, the rights of minorities and refugees, and the right of peoples to self-determination. The LON also gave rise to specialised bodies such as the International Labour Organization (ILO) or the Health Committee.

Its aspiration was universalist and egalitarian: the voice of small states, such as Luxembourg, carried the same weight as that of large states. However, the LON never succeeded in gaining the support of all the major nations: Germany was excluded until 1926, the United States never joined, and other member states withdrew to pursue their unilateral policies—often in violation of the League’s principles.

The lack of effective enforcement mechanisms and the inability to impose sanctions on states that violated the rules, the imperialist and belligerent activities of fascist and nationalist regimes, and economic protectionism in the context of the global economic crisis ultimately led to the League’s demise. Despite its many shortcomings, the LON also succeeded in peacefully resolving numerous interstate disputes. The lessons learned from this first experience of a permanent international organisation would later help to create the United Nations.

Even before the end of the Second World War, the Allied powers decided to create a new multilateral institution to replace the moribund League of Nations. On 26 June 1945, 51 countries, including Luxembourg, signed the Charter of the United Nations, which listed international peace and security among the UN’s main objectives. The idea put forward by Grand Duchess Charlotte to choose Luxembourg as the seat of this new organisation had been seriously considered but was ultimately rejected, as the headquarters were eventually established in New York. This is where the two central organs of the UN architecture are now located: the General Assembly (UNGA) and the Security Council (UNSC).

The UNGA brings together all signatories of the UN Charter, and all countries have equal voting rights. It currently counts 191 member states. The annual debates held there provide a global forum for governments to express their concerns about world affairs and international security. In 1975, Luxembourgish politician Gaston Thorn was elected president of the 30^th session of the UNGA by a majority of member states, a significant moment in Luxembourg’s history of multilateralism.

The most powerful body of the UN is the UNSC. It alone has the right to authorise the use of military force in the name of collective security if all peaceful options have failed. The UNSC comprises five permanent members—China, France, Russia, the United Kingdom, and the United States—as well as ten non-permanent members elected for a two-year term. Luxembourg first served on the UNSC in 2013/2014 and is now applying for a second term for 2031/2032.

The UNSC, more than other UN bodies, is the subject of much criticism. The composition of the permanent members is not representative, as it includes no countries from Latin America, Africa, or the Middle East. Furthermore, the veto power of the permanent members is considered outdated, counterproductive, and undemocratic.

Critics of multilateralism accuse it of inefficiency and useless discussions, arguing that it often fails to implement the necessary changes on the ground, as unilateral actions would do. Another criticism maintains that too little power and influence are given to civil society, while too much power resides within states, which too often prioritise their own national interests. As part of the UN’s 80th anniversary in 2025,, Secretary-General António Guterres announced sweeping reforms to the UN’s overall structure, dubbed UN80, to make the multilateral organisation more effective.

In 2012, the European Union (EU) was awarded the Nobel Peace Prize for its contribution to peace, reconciliation, and democracy on the continent. The idea of overcoming national rivalries to create a ‘United States of Europe’ dates back at least to the 19th century. Yet, it took two devastating wars to establish a common political and economic system. European integration made it possible to ban wars between European states and to foster cooperation between former long-standing enemies, in particular Germany and France. This integration, however, was not purely idealistic: it also aimed to unite Western Europe against the new communist enemy on the other side of the Iron Curtain.

Luxembourg supported and participated in the creation of common political structures in Europe from the outset. It is a founding member of the Organisation for European Economic Cooperation (OEEC) in 1948 and of the Council of Europe in 1949. Most importantly, it is one of the six founding members of the European Coal and Steel Community (ECSC), launched in 1950 by Robert Schuman, the French Foreign Minister of Luxembourgish origin. This supranational organisation placed coal and steel—crucial resources in both world wars—under a common authority. The ECSC is often considered the precursor to the European Economic Community (EEC), which later became the EU. Since 1965, Luxembourg has been one of the three capitals of the EU, alongside Brussels and Strasbourg, and is home to several of the main community institutions. The Luxembourgish town of Schengen, located on the border with Germany and France, is also the namesake of the 1985 treaty that introduced open borders in the EU.

The Russian military invasion of Ukraine shook the European Union to its core. War crimes committed on European soil by a non-Atlantic neighbour against a friendly nation have challenged long-held political certainties.

Although this is not the first armed conflict in post-war Europe—one need only recall the Troubles in Northern Ireland (1968–1998), the Nagorno-Karabakh conflict since 1988, the violent breakup of Yugoslavia (1991–2001), the wars in Chechnya (1994–2000), or the 2008 Russo-Georgian War—it is the war between Russia and Ukraine that has caused a profound shift in the security landscape. Strengthening military capabilities is now viewed as a condition for safeguarding European peace against an external threat—in this instance, Russia. With this in mind, European states have opted to significantly increase military spending and accelerate the production and development of weaponry. Some countries are considering reintroducing mandatory military service, and a shared European nuclear umbrella for deterrence is also in discussion.

While some view this rearmament and remilitarisation as a guarantee of peace, others see these developments as a dangerous escalation that risks, sooner or later, igniting a wider conflict.