Withdrawal from NATO is the legal and political process whereby a member of the North Atlantic Treaty Organisation (NATO) withdraws from the North Atlantic Treaty, and thus the country in question ceases to be a member of NATO. The formal process is stated in article 13 of the Treaty. This says that any country that wants to leave must send the United States (as the depositary state) a "notice of denunciation", which the U.S. would then pass on to the other Allies. After a one-year waiting period, the country that wants to leave would be out.

As of , no member state has rescinded their membership, although it has been considered by several countries. Notwithstanding, a number of former dependencies of NATO members have never applied for membership subsequent to their becoming independent states.

Procedure Article 13 of the North Atlantic Treaty is the article that member states use for informing other members or parties that it wishes to leave the North Atlantic Treaty Organisation. It states the following:After the Treaty has been in force for twenty years, any Party may cease to be a Party one year after its notice of denunciation has been given to the Government of the United States of America, which will inform the Governments of the other Parties of the deposit of each notice of denunciation.This means that after 20 years since the signing of the original treaty, which was in 1949, thus since 1969, any member state that wishes to leave just has to inform the United States that it wants to leave, and then after a year it formally leaves.

Despite calls for a number of countries, including Turkey, to be expelled from NATO, there is no mechanism in the treaty for expelling member states, only voluntary withdrawals. This was confirmed by secretary general Jens Stoltenberg in 2021 at a meeting in Riga, Latvia.

Contemplated withdrawals Bulgaria The far-right Revival party supports Bulgarian withdrawal from NATO.

Canada Canada is a founding member of NATO and remains a member. In 2019, the Green Party advocated a review of Canadian membership of the alliance. The position of the social-democratic New Democratic Party is complicated; while there is general support for NATO membership within the party, including from former party leaders Jack Layton and Tom Mulcair, the NDP Socialist Caucus advocates revoking Canada's membership. Some of the reasons for opposition to membership of the alliance include membership being incompatible to the Canadian tradition of peacekeeping and concerns of Canadian sovereignty over its defence forces.

, the Canadian political consensus is to support NATO membership as part of national defence policy. Parties with representation in the Parliament of Canada that support NATO membership include the governing Liberal Party, the opposition Conservative Party, and the Quebec sovereigntist Bloc Québécois.

Denmark The far-left Enhedslisten until 2022 supported withdrawal from NATO. The party subsequently adopted a position affirming a critical approach towards NATO but no longer supporting withdrawal until an "alternative" exists.

France In 1966, due to souring relations between Washington and Paris because of the refusal to integrate France's nuclear deterrent with other North Atlantic powers, or to accept any collective form of control over its army, French president Charles de Gaulle downgraded France's membership in NATO and withdrew France from the NATO Military Command Structure to pursue more independent defense options. However, he also stated that France would remain in the alliance even after the end of the 20-year commitment period in 1969, unless the "fundamental elements of the relations between East and West" changed.

In 1967, following de Gaulle's decision, all of NATO's 30-odd bases in France (consisting mostly of U.S. forces) were evacuated, along with 27,000 troops and 37,000 civilians.Paul-Marie de La Gorce, "Retour honteux de la France dans l'OTAN [archive]," Le Monde diplomatique, January 1996. NATO headquarters left les Yvelines and moved to Belgium.

In 2009, France rejoined the NATO Military Command Structure. The reversal was announced by President Nicolas Sarkozy and backed by the Parliament of France.

Currently, of the noted political parties in France; those advocating withdrawal from NATO include the souverainist Popular Republican Union,Schrepf, Jerôme. "Villeneuve-sur-lot. L'UPR entre conquête et résistance", LaDépêche.fr, 24 May 2013. Retrieved on 1 October 2013 together with the left-wing La France Insoumise and the far left French Communist Party. The right-wing Gaullist Debout la France and the nationalist National Rally advocate reversing the 2009 decision for France returning to NATO command. In a July 2024 poll, 54% of French people viewed NATO favorably, and 37% unfavorably.

Germany During the conversations leading to the German reunification, the Soviet Union sought to move the union of West Germany (in NATO) and East Germany (in the Warsaw Pact) into neutrality and de-nuclearization. However, West German chancellor Helmut Kohl and American president George H. W. Bush wanted the united Germany to remain in NATO in spite of considerable scepticism among West Germans wanting to remain in NATO after the reunification (as low as 20% according to a SPIEGEL report). Mikhail Gorbachev finally removed the Soviet objection and the new eastern territories of Germany became covered by NATO on the condition that no foreign forces or weapons of mass destruction were to be located on them.

Die Linke, a left-wing political party in the Bundestag opposes military alliances, including NATO membership.

Greece

In 1974 due to the Cyprus crisis, Greece withdrew military units from NATO forces in the Southern Mediterranean, over threats of invasion of Cyprus by fellow NATO member Turkey. Later in 1974 due to the invasion of Cyprus by Turkish forces, Greece withdrew from the NATO military command. Notwithstanding, the country did not withdraw entirely from the organisation, but became significantly less active.

In 1980, the Greek foreign minister Konstantinos Mitsotakis made remarks about the situation where he could see Greece fully withdrawing from the organisation. However, later diplomatic pressure from the United States led to Greece fully re-integrating with the alliance.

According to a poll conducted in 2022, NATO remains popular among the Greek public with 78% wanting to remain in the alliance and only 18% wanting to leave.

Iceland Iceland is unique amongst NATO members in that it does not have a standing army, and its defence forces consist of a militarised coastguard and a paramilitary peacekeeping force. Iceland's strong pacifist history has led to considerable opposition to NATO membership in Iceland. Nevertheless, the country was a host to the notable United States Navy base at Keflavík airport, near the country's capital Reykjavík.

The country's main nonpartisan pressure group for Iceland leaving NATO is , which is a branch of War Resisters' International.

In 2019, during a visit by the Secretary-General Jens Stoltenberg to Iceland, Prime Minister Katrín Jakobsdóttir spoke of her support for withdrawing Iceland from NATO. Her party, the Left-Green Movement, is the senior partner of the Icelandic government, which also supports withdrawing, but there is not a majority in the Icelandic parliament for withdrawing. , she continues to oppose Icelandic membership in NATO.

A Gallup poll taken in April 2025 showed that 71% of Icelanders supported the country's NATO membership, while 12% were opposed.

Montenegro Several political parties in Montenegro, including New Serb Democracy and the Democratic People's Party, oppose NATO membership. The 2020 Montenegrin parliamentary election resulted in a victory for these parties for the first time in 30 years. However, these parties did not formally pursue withdrawal upon taking office.

North Macedonia The left-wing Levica party supports withdrawal of North Macedonia from NATO.

Netherlands The Dutch consensus about foreign and defence policy is to remain a member of the alliance. Its membership is supported by all five main establishment parties in the Staten-General; the conservative-liberal VVD, the social-democratic PvdA, the Christian-democrat CDA, right-wing populist PVV, and social-liberal D66. Other parties are supportive but would like to reform the alliance, such as the green-social democratic GroenLinks.

While the far-right populist Forum voor Democratie supports NATO membership, it was reported by the investigative show Zembla that privately the party's leader Thierry Baudet would like the Netherlands to leave NATO and align the country's foreign policy with Russia.

Romania Some minor political parties in Romania oppose Romanian membership in NATO. One of them is Noua Dreaptă, which is also against the European Union.

Spain Spain joined the alliance in 1982 under the UCD-led conservative government of Calvo-Sotelo. However, this was opposed by a significant portion of Spanish society especially on the left and pacifist groups. Under the social democratic González government in March 1986, Spain had a referendum on NATO membership in which both the main social democratic PSOE and conservative AP parties supported membership. The result was a "yes" vote, but with strong opposing results in separatist regions of the Canary Islands, Basque Country, Navarre and Catalonia. Opposition to NATO led to the creation of the left-wing United Left-linked pacifist pressure group “La Plataforma Cívica por la Salida de España de la OTAN”. Although the referendum result was conditional on a stipulated non-integration of Spain’s armed forces into NATO's structure, in 1996 Spain fully joined NATO.

Today, membership is opposed by a number of left-wing and separatist political parties. These include the left-wing United Left and Podemos, Basque separatist EH Bildu, Galician nationalist BNG and left-wing Catalan-separatist CUP who have either advocated withdrawal or downgrading Spain’s membership. Other groups that support Spanish withdrawal include the State Coordination Against NATO and Bases (CECOB) and the Coordinator for Total Disarmament and Denuclearization (CDDT).

Slovakia The far-right Republic Movement party advocates for the withdrawal of Slovakia from NATO.

Turkey

Since the 2016 attempted coup d'état, the 2019 Turkish Offensive into northeastern Syria, the deterioration of relations between Turkey and the United States, the deterioration of relations between Greece and Turkey, warming relations between Turkey and Russia, and opposition towards Finland and Sweden in their membership bids in 2022 which led to delays in joining the alliance, there have been calls for Turkey to leave or be thrown out of NATO.

Inside Turkey, politicians like the Nationalist Movement Party (MHP) leader Devlet Bahçeli suggested that Turkey leaving NATO should be considered an option. In May 2022, opposition leader Kemal Kılıçdaroğlu said that if the Justice and Development Party and the Nationalist Movement Party decided to close the Incirlik Air Base to NATO, the Republican People's Party would also support it.

United Kingdom

The established consensus of the United Kingdom's defence and foreign policy framework includes full membership and participation of NATO. Membership is supported by both major parties in the UK (The Conservatives and Labour) and the Liberal Democrats.