Background (pre-1941) at the
League of Nations appealing Italy's 1936 invasion in which the League failed to intervene. In the century prior to the UN's creation, several
international organizations such as the
International Committee of the Red Cross were formed to ensure protection and assistance for victims of armed conflict and strife. During
World War I, several major leaders, especially
U.S. president Woodrow Wilson, advocated for a world body to guarantee peace. The winners of the war, the
Allies, met to decide on formal peace terms at the
Paris Peace Conference. The
League of Nations was approved and started operations, but the
United States never joined. On 10 January 1920, the League of Nations formally came into being when the
Covenant of the League of Nations, ratified by 42 nations in 1919, took effect. The League Council acted as an executive body directing the Assembly's business. It began with four permanent members—the
United Kingdom,
France,
Italy, and
Japan. After some limited successes and failures during the 1920s, the League proved ineffective in the 1930s, as it failed to act against the
Japanese invasion of Manchuria in 1933. Forty nations voted for Japan to withdraw from
Manchuria but Japan voted against it and walked out of the League instead of withdrawing from Manchuria. It also failed to act against the
Second Italo-Ethiopian War, after the appeal for international intervention by
Ethiopian Emperor Haile Selassie I at Geneva in 1936 went with no avail, including when calls for economic sanctions against Italy failed. Italy and other nations left the League. When
World War II broke out in 1939, the League effectively closed down.
Declarations by the Allies of World War II (1941–1944) , an executive branch, and an international assembly of forty UN member states. The first step towards the establishment of the United Nations was the Inter-Allied Conference in London that led to the
Declaration of St James's Palace on 12 June 1941. By August 1941, American president
Franklin Roosevelt and British prime minister
Winston Churchill had drafted the
Atlantic Charter; which defined goals for the post-war world. At the subsequent meeting of the Inter-Allied Council in London on 24 September 1941, the eight
governments in exile of countries under Axis occupation, together with the
Soviet Union and representatives of the
Free French Forces, unanimously adopted adherence to the common principles of policy set forth by Britain and the United States. Roosevelt and Churchill met at the
White House in December 1941 for the
Arcadia Conference. Roosevelt is considered a founder of the UN, and coined the term
United Nations to describe the
Allied countries. Churchill accepted it, noting its use by
Lord Byron. The text of the
Declaration by United Nations was drafted on 29 December 1941, by Roosevelt, Churchill, and
Harry Hopkins. It incorporated Soviet suggestions but included no role for France. One major change from the Atlantic Charter was the addition of a provision for
religious freedom, which Stalin approved after Roosevelt insisted. Roosevelt's idea of the "
Four Powers", refers to the four major Allied countries, the United States, the United Kingdom, the Soviet Union, and
China, emerged in the Declaration by the United Nations. On New Year's Day 1942, Roosevelt, Churchill, the Soviet Union's former Foreign Minister
Maxim Litvinov, and the Chinese Premier
T. V. Soong signed the "
Declaration by United Nations", and the next day the representatives of twenty-two other nations added their signatures. During the war, the United Nations became the official term for the Allies. In order to join, countries had to sign the Declaration and declare war on the
Axis powers. The October 1943
Moscow Conference resulted in the
Moscow Declarations, including the
Four Power Declaration on General Security. This declaration was signed by the
Allied Big Four—the United States, the Soviet Union, the United Kingdom, and China—and aimed for the creation "at the earliest possible date of a general international organization". This was the first public announcement that a new international organization was being contemplated to replace the League of Nations. The
Tehran Conference followed shortly afterwards at which Roosevelt, Churchill and
Joseph Stalin, the leader of the Soviet Union, met and discussed the idea of a post-war international organization. The new international organization was formulated and negotiated amongst the delegations from the
Allied Big Four at the
Dumbarton Oaks Conference from 21 September to 7 October 1944. They agreed on proposals for the aims, structure and functioning of the new organization. It took the
conference at Yalta in February 1945, and further negotiations with the Soviet Union, before all the issues were resolved. The delegations of the Big Four chaired the plenary meetings. Previously, Churchill had urged Roosevelt to restore France to its status of a major power after the
liberation of Paris in August 1944. The drafting of the
Charter of the United Nations was completed over the following two months, and it was signed on 26 June 1945 by the representatives of the 50 countries. The UN officially came into existence at 20:07 (
UTC) on 24 October 1945, upon ratification of the Charter by the five permanent members of the
Security Council: the United States, the United Kingdom, France, the Soviet Union and
China — and by a majority of the other 46 nations. The
first meetings of the
General Assembly, with 51 nations represented, and the Security Council took place in
London beginning in January 1946. Debates began at once, covering topical issues such as the presence of Russian troops in
Iranian Azerbaijan and British forces in
Greece. British diplomat
Gladwyn Jebb served as interim secretary-general. The General Assembly selected
New York City as the site for the headquarters of the UN. Construction began on 14 September 1948 and the facility was completed on 9 October 1952. The Norwegian Foreign Minister,
Trygve Lie, was the first elected
UN secretary-general. On 29 November 1947, the General Assembly approved
Resolution 181, a proposal to partition British Mandatory
Palestine into two states, a Jewish state and an Arab state, with Jerusalem placed under international status. The Partition plan passed 33–13 with 10 abstentions and one absent. The plan was accepted by the Jews and rejected by the Arabs of Palestine and the Arab states leading to
civil war. Following the declaration of the State of Israel on 15 May 1948, the surrounding Arab armies invaded Palestine, beginning the
1948 Arab–Israeli War. Two years later,
Ralph Bunche, a UN official, negotiated
an armistice to the
resulting conflict, with the Security Council deciding that "an armistice shall be established in all sectors of Palestine". however, the UN was unable to intervene against the Soviet Union's simultaneous invasion of
Hungary, following
the country's revolution. On 14 July 1960, the UN established the
United Nations Operation in the Congo (or UNOC), the largest military force of its early decades, to bring order to
Katanga, restoring it to the control of the
Democratic Republic of the Congo by 11 May 1964. While travelling to meet rebel leader
Moise Tshombe during the conflict,
Dag Hammarskjöld, often named as one of the UN's most effective secretaries-general,
died in a plane crash. Months later he was posthumously awarded the
Nobel Peace Prize. In 1964, Hammarskjöld's successor,
U Thant, deployed the
UN Peacekeeping Force in Cyprus, which would become one of the UN's longest-running peacekeeping missions. With the spread of
decolonization in the 1960s, the UN's membership shot up due to an influx of newly independent nations. In 1960 alone, 17 new states joined the UN, 16 of them from Africa. With an increasing Third World presence and the failure of UN mediation in conflicts in the
Middle East,
Vietnam, and
Kashmir, the UN increasingly shifted its attention to its secondary goals of economic development and cultural exchange. By the 1970s, the UN budget for social and economic development was far greater than its peacekeeping budget.
Post-Cold War (1991–1999) , secretary-general from 1997 to 2006 , pictured in 2007 After the Cold War, the UN saw a radical expansion in its peacekeeping duties, taking on more missions in five years than it had in the previous four decades. Between 1988 and 2000, the number of adopted Security Council resolutions more than doubled, and the peacekeeping budget increased more than tenfold. The UN negotiated an end to the
Salvadoran Civil War, launched a successful
peacekeeping mission in Namibia, and oversaw democratic elections in post-
apartheid South Africa and post-
Khmer Rouge Cambodia. In 1991, the UN authorized a
US-led coalition that repulsed Iraq's
invasion of Kuwait.
Brian Urquhart, the under-secretary-general of the UN from 1971 to 1985, later described the hopes raised by these successes as a "false renaissance" for the organization, given the more troubled missions that followed. Beginning in the last decades of the
Cold War, critics of the UN condemned the organization for perceived mismanagement and corruption. In 1984, American president
Ronald Reagan withdrew the United States' funding from the
United Nations Educational, Scientific and Cultural Organization (or UNESCO) over allegations of mismanagement, followed by the United Kingdom and Singapore.
Boutros Boutros-Ghali, the secretary-general from 1992 to 1996, initiated a reform of the Secretariat, somewhat reducing the size of the organization. Though the UN Charter had been written primarily to prevent aggression by one nation against another, in the early 1990s the UN faced several simultaneous, serious crises within Somalia, Haiti, Mozambique, and the nations that previously made up Yugoslavia. The
UN mission in Somalia was widely viewed as a failure after the United States' withdrawal following casualties in the
Battle of Mogadishu. The
UN mission to Bosnia faced worldwide ridicule for its indecisive and confused mission in the face of ethnic cleansing. In 1994, the
UN Assistance Mission for Rwanda failed to intervene in the
Rwandan genocide amidst indecision in the Security Council. From the late 1990s to the early 2000s, international interventions authorized by the UN took a wider variety of forms. The
United Nations Security Council Resolution 1244 authorized the
NATO-led
Kosovo Force beginning in 1999. The
UN mission in the
Sierra Leone Civil War was supplemented by a
British military intervention. The
invasion of Afghanistan in 2001 was overseen by NATO. In 2003, the United States
invaded Iraq despite failing to pass a UN Security Council resolution for authorization, prompting a new round of questioning of the UN's effectiveness. Under the eighth secretary-general,
Ban Ki-moon, the UN intervened with peacekeepers in crises such as the
War in Darfur in Sudan and the
Kivu conflict in the Democratic Republic of the Congo and sent observers and chemical weapons inspectors to the
Syrian Civil War. In 2013,
an internal review of UN actions in
the final battles of the
Sri Lankan Civil War in 2009 concluded that the organization had suffered a "systemic failure". In 2010, the organization suffered the worst loss of life in its history, when 101 personnel died in the
Haiti earthquake. Acting under the
United Nations Security Council Resolution 1973 in 2011,
NATO countries intervened in the
First Libyan Civil War. The
Millennium Summit was held in 2000 to discuss the UN's role in the 21st century. The three-day meeting was the largest gathering of world leaders in history, and it culminated in the adoption by all member states of the
Millennium Development Goals (or MDGs), a commitment to achieve international development in areas such as
poverty reduction,
gender equality and
public health. Progress towards these goals, which were to be met by 2015, was ultimately uneven. The
2005 World Summit reaffirmed the UN's focus on promoting development, peacekeeping, human rights and global security. The
Sustainable Development Goals (or SDGs) were launched in 2015 to succeed the Millennium Development Goals. In addition to addressing global challenges, the UN has sought to improve its accountability and democratic legitimacy by engaging more with
civil society and fostering a global constituency. In an effort to enhance transparency, in 2016 the organization held its first public debate between candidates for secretary-general. On 1 January 2017, Portuguese diplomat
António Guterres, who had previously served as the
UN High Commissioner for Refugees, became the ninth secretary-general. Guterres has highlighted several key goals for his administration, including an emphasis on diplomacy for preventing conflicts, more effective peacekeeping efforts, and streamlining the organization to be more responsive and versatile to international needs. On 13 June 2019, the UN signed a Strategic Partnership Framework with the
World Economic Forum in order to "jointly accelerate" the implementation of the
2030 Agenda for Sustainable Development.
2020s: financial crisis Throughout most of its history, the UN has faced funding issues. However, they have become severe since 2020, and in 2025, the UN began facing a financial crisis resulting from delays in member state due payments and refusal to pay the amount the UN charges. A major problem is that the United States, the largest contributor, has a law in place since 1994 where it will not pay more than 25% of total UN Peacekeeping fees (although as of 2024 it was paying 27%). Additionally, the US and the second largest contributor, China, often delay their payments in order to influence the UN on topics such as the
Gaza war and
Persecution of Uyghurs in China. Other countries began to follow suit, triggering a financial crisis. On 19 May 2025, only 61 countries paid their dues on time and in full. In January 2026, Guterres sent a letter to all members about an "imminent financial collapse" of the UN. == Structure ==