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NATO

NATO, the North Atlantic Treaty Organization, is an alliance founded on the North Atlantic Treaty signed in 1949, with collective defence as its core principle. Its political and administrative centre is in Brussels, Belgium.

Contents21 sections
Key facts

The Vandenberg Resolution and Secret Talks

The North Atlantic Treaty Is Signed

On April 4, 1949, the 12 founding members — Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the United Kingdom and the United States — signed the North Atlantic Treaty, also known as the Washington Treaty, at the Departmental Auditorium in Washington, D.C.; Secretary of State Dean Acheson signed for the United States.⁠[2][1]

July–August 1949: U.S. Ratification and the First Headquarters

On July 21, 1949, the U.S. Senate approved the treaty by 83 votes to 13, and on July 25 President Harry S. TrumanHarry S. TrumanHarry S. Truman (1884–1972) was an American politician who served as a U.S. senator from Missouri and as vice president in 1945, succeeding Franklin D. Roosevelt on his death that year and serving as the 33rd president of the United States from 1945 to 1953, a period spanning the end of World War II and the early Cold War.Open the full entry and Acheson signed the instrument of accession, making the United States a founding member. On August 24 Truman said the treaty aimed to establish “freedom from aggression and from the use of force” in the North Atlantic community.⁠[1]

In 1949 NATO’s first headquarters was at 13 Belgrave Square in London.⁠[3]

Dwight D. Eisenhower as First Supreme Allied Commander Europe

The North Atlantic Council created the post of Supreme Allied Commander Europe (SACEUR) in 1950 and on December 19, 1950, announced General Dwight D. EisenhowerDwight D. EisenhowerDwight D. Eisenhower (1890–1969) was an American army general and politician who served as supreme commander of Allied forces in western Europe during World War II and as the 34th president of the United States, a Republican, from 1953 to 1961.Open the full entry as its first holder. Eisenhower arrived in Paris on January 1, 1951, and on April 2, 1951, signed the activation order for Allied Command Europe and its headquarters, SHAPE, which operated first from the Hotel Astoria in central Paris and from July 1951 from a permanent complex in the Paris suburb of Rocquencourt.⁠[4][1]

By March 1951, 101 of the 150 officers at SHAPE were Americans. In 1952 Eisenhower resigned as SACEUR and went on to become the 34th President of the United States; that year the Council also approved Allied Command Atlantic in Norfolk, VirginiaVirginiaVirginia, officially the Commonwealth of Virginia, is a U.S. state whose capital is Richmond. It entered the Union on June 25, 1788, as the 10th state, and had a population of 8,631,393 in the 2020 census (April 1, 2020).Open the full entry, under a U.S. Navy admiral.⁠[1]

First Enlargement and the Move to Paris

Greece and Türkiye joined NATO on February 18, 1952, in its first enlargement. In April 1952 the headquarters moved to central Paris, first to the Palais de Chaillot and in 1960 to a purpose-built building at Porte Dauphine.⁠[5][3]

West Germany and Spain Join

The Federal Republic of Germany joined NATO on May 6, 1955, and Spain on May 30, 1982.⁠[5]

The Move to Brussels

After France withdrew from NATO’s integrated military command in 1966, the headquarters moved to Brussels, where a site built in six months was inaugurated on October 16, 1967.⁠[3]

Central and Eastern European Members

Czechia, Hungary and Poland joined NATO on March 12, 1999, and Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia on March 29, 2004.⁠[5]

Article 5 Invoked for the First Time

On the evening of September 12, 2001, less than 24 hours after the 9/11 attacks on the United States, the Allies invoked Article 5 for the first time in NATO’s history; on October 2, 2001, after being briefed on the results of the investigation, the North Atlantic Council determined that the attacks were covered by Article 5.⁠[6]

NATO’s first anti-terror operation, Operation Eagle Assist, ran from mid-October 2001 to mid-May 2002, with seven NATO AWACS radar aircraft patrolling U.S. skies and 830 crew members from 13 countries flying more than 360 sorties. Operation Active Endeavour, launched on October 26, 2001, sent Standing Naval Forces to patrol the Eastern Mediterranean and monitor shipping, and was extended to the entire Mediterranean in March 2004.⁠[6]

Balkan Members

Albania and Croatia joined NATO on April 1, 2009, Montenegro on June 5, 2017, and North Macedonia on March 27, 2020.⁠[5]

Strengthening Collective Defence

After Russia annexed Crimea in 2014, NATO carried out the biggest reinforcement of collective defence since the Cold War: it tripled the size of the NATO Response Force, created a 5,000-strong Spearhead Force, and deployed multinational battlegroups in Estonia, Latvia, Lithuania and Poland and a brigade in Romania. Cyberspace was recognized as an operational domain at the Warsaw Summit in July 2016, and space in November 2019.⁠[6]

After Russia’s invasion of Ukraine in February 2022, the NATO Response Force was deployed for the first time in a deterrence and defence role, and at an extraordinary summit on March 24, 2022, leaders agreed to significantly strengthen the Alliance’s longer-term posture.⁠[6]

The New Headquarters

A new headquarters across the road from the old one, decided in 1999, was completed in 2017, and NATO moved in during 2018.⁠[3]

Finland and Sweden Join

Finland joined NATO on April 4, 2023, and Sweden on March 7, 2024, bringing the membership to 32 countries, up from 12 founding members in 1949.⁠[5]

Mark Rutte Becomes the 14th Secretary General

Mark Rutte, a former Prime Minister of the Netherlands, took office as NATO’s 14th Secretary General on October 1, 2024, succeeding Jens Stoltenberg, who had served since 2014.⁠[7][8]

The Hague Summit Sets a 5% Target

On June 25, 2025, NATO heads of state and government meeting in the North Atlantic Council in The Hague issued The Hague Summit Declaration, committing Allies to invest 5% of GDP annually by 2035 on core defence and defence- and security-related spending: at least 3.5% on core defence and up to 1.5% on areas such as critical infrastructure, networks, civil preparedness, resilience, innovation and the defence industrial base. The trajectory and balance are to be reviewed in 2029, and direct contributions to Ukraine’s defence and defence industry count toward Allies’ defence spending. The declaration reaffirmed the commitment to Article 5.⁠[9]

The Ankara Summit

The NATO Summit was held at the Beştepe Presidential Complex in Ankara, Türkiye, on July 7–8, 2026, and the Ankara Summit Declaration was issued on July 8. NATO states that European Allies and Canada had increased core defence investment by more than USD 139 billion since the 2025 Hague commitment; at the summit Allies announced more than EUR 50 billion in procurement deals, agreed to invest over USD 40 billion over five years in counter-drone capabilities and committed EUR 27 billion to modernize fuel storage and distribution infrastructure. Allies pledged EUR 70 billion in military equipment, assistance and training for Ukraine for 2026, with at least an equivalent level for 2027.⁠[10]

As of November 2026: Secretary General and Headquarters

As of November 2026 Rutte remains Secretary General. NATO Headquarters on Boulevard Leopold III in Brussels is the permanent home of the North Atlantic Council and houses the national delegations of member countries, liaison offices or missions of partner countries, and the International Staff and International Military Staff; as of March 2024 it had about 4,000 full-time staff and hosted some 6,000 meetings a year.⁠[7][3]

Key Provisions of the North Atlantic Treaty

The North Atlantic Treaty has 14 articles and has never been modified; new members join through accession protocols. Article 5 provides for collective defence — an attack against one Ally is considered an attack against all — with each member deciding for itself what assistance, not necessarily military, it considers necessary; Article 6 defines the geographic scope of Article 5; Article 10, the basis of NATO’s “open door policy,” allows any “European State in a position to further the principles of this Treaty” and to contribute to the security of the North Atlantic area to be invited to join; and Articles 12 and 13 allow a review after 10 years and withdrawal only after 20 years, provisions that have never been used.⁠[2][6][5]

The Secretary General

The Secretary General is NATO’s top international civil servant, chairing major committees including the North Atlantic Council, acting as the Alliance’s principal spokesperson and heading the International Staff; the post-holder is nominated by member governments for an initial four-year term, which can be extended by mutual consent.⁠[8]

Before Rutte, the Secretaries General were Lord Ismay (1952–1957), Paul-Henri Spaak (1957–1961), Dirk U. Stikker (1961–1964), Manlio Brosio (1964–1971), Joseph Luns (1971–1984), Lord Carrington (1984–1988), Manfred Wörner (1988–1994), Willy Claes (1994–1995), Javier Solana (1995–1999), Lord Robertson of Port Ellen (1999–2003), Jaap de Hoop Scheffer (2004–2009), Anders Fogh Rasmussen (2009–2014) and Jens Stoltenberg.⁠[8][7]

Related Organizations, Websites, and Public Accounts

Sources

  1. United States and NATO (opens in a new window)
  2. Founding treaty (opens in a new window)
  3. NATO Headquarters (opens in a new window)
  4. 1949-1952: Creating a Command Structure for NATO (opens in a new window)
  5. Enlargement and Article 10 (opens in a new window)
  6. Collective defence - Article 5 (opens in a new window)
  7. NATO Secretary General (opens in a new window)
  8. NATO Secretary General (opens in a new window)
  9. The Hague Summit Declaration (opens in a new window)
  10. Overview - 2026 NATO Summit in Ankara (opens in a new window)