NATO (the North Atlantic Treaty Organization) maintains foreign relations with many non-member countries across the globe. NATO runs a number of programs which provide a framework for the partnerships between itself and these non-member nations, typically based on that country's location. These include the Euro-Atlantic Partnership Council and the Partnership for Peace.

European Union

23 out of the 27 EU member states are members of NATO. Four EU member states, who have declared their non-alignment with military alliances, are: Austria, Cyprus, Ireland, and Malta. All these countries except Cyprus have joined the Partnership for Peace programme.

Austria

Austria was occupied by the four victorious Allied powers following World War II under the Allied Control Council, similar to Germany. During negotiations to end of the occupation, which were ongoing at the same time as Germany's, the Soviet Union insisted on the reunified country adopting the model of Swiss neutrality. The US feared that this would encourage West Germany to accept similar Soviet proposals for neutrality as a condition for German reunification. Shortly after West Germany's accession to NATO, the parties agreed to the Austrian State Treaty in May 1955, which was largely based on the Moscow Memorandum signed the previous month between Austria and the Soviet Union. While the treaty itself did not commit Austria to neutrality, this was subsequently enshrined into Austria's constitution that October with the Declaration of Neutrality. The Declaration prohibits Austria from joining a military alliance, from hosting foreign military bases within its borders, and from participating in a war.

Membership of Austria in the European Union (or its predecessor organizations) was controversial due to the Austrian commitment to neutrality. Austria only joined in 1995, together with two Nordic countries that had also declared their neutrality in the Cold War (Sweden and Finland). Austria joined NATO's Partnership for Peace in 1995, and participates in NATO's Euro-Atlantic Partnership Council. The Austrian military also participates in the United Nations peacekeeping operations and has deployments in several countries , including Kosovo, Lebanon, and Bosnia and Herzegovina, where it has led the EUFOR mission there since 2009. Conservative politician Andreas Khol, the 2016 presidential nominee from the Austrian People's Party (ÖVP), has argued in favor of NATO membership for Austria in light of the 2022 Russian invasion of Ukraine, and Chancellor from 2000 to 2007, Wolfgang Schüssel, also of the ÖVP, supported NATO membership as part of European integration. Current Chancellor Karl Nehammer, however, has rejected the idea of reopening Austria's neutrality and membership is not widely popular with the Austrian public.

According to a survey in May 2022 by the Austria Press Agency, only 14% of Austrians surveyed supported joining NATO, while 75% were opposed. Following the accession of Finland and Sweden into NATO in 2023 and 2024 respectively, there have been renewed debates on Austria joining the bloc, similar to how Austria joined the EU alongside Finland and Sweden. On 8 May 2022, a coalition of politicians, diplomats, artists and businesspeople wrote an open letter to the Austrian government asking them to review their commitment to neutrality. However, the only party to support the effort was NEOS, which holds 15 of the 183 seats in the National Council. On 3 March 2023, another survey was held by the Austrian Society for European Politics on NATO ascension which found 21% are in favor with 61% against. This was an increase of both 7% in favor and 7% unsure, compared to the last survey 10 months prior.

Cyprus

Cyprus is the only EU member state that is neither a NATO member state nor a member of the PfP program. The Parliament of Cyprus voted in February 2011 to apply for membership in the program, but President Demetris Christofias vetoed the decision, arguing that it would hamper his attempts to negotiate an end to the Cyprus dispute and demilitarize the island. Turkey, a full member of NATO, is likely to veto any attempt by Cyprus to engage with NATO until the dispute is resolved. Nicos Anastasiades, who was elected President in 2013, stated that he intended to apply for membership in the PfP program soon after taking over. His foreign minister Nikos Christodoulides later dismissed Cypriot membership of NATO or Partnership for Peace, preferring to keep Cyprus' foreign and defence affairs within the framework of the EU, i.e. the Common Security and Defence Policy (CSDP).

After the 2023 presidential election, Anastasiades' foreign minister Christodoulides succeeded him as president. In November 2024, Christodoulides reversed his previous stance and revealed a plan to deepen Cyprus' relations with NATO and eventually join as a full member. Under the first phase of the plan, Cyprus would seek to join preparatory organizations linked to NATO, which would require progress in resolving the Cyprus dispute with NATO member Turkey and improvements to EU–Turkey relations. Practical steps of the plan include securing a longer-term exemption from the U.S. arms embargo, expanding joint military training opportunities for the Cypriot National Guard at U.S. military academies, and modernization of Cyprus' defense infrastructure to meet NATO standards. Christodoulides stated that "the U.S. response has been very positive" and that these steps "will ensure that, once all conditions are met, Cyprus can join NATO".

Ireland

Ireland has been a member of NATO's Partnership for Peace (PfP) programme since 1999, and is a member of the alliance's Euro-Atlantic Partnership Council (EAPC), but has never officially applied to join as a full NATO member due to its traditional policy of military neutrality. Ireland participates in the PfP Planning and Review Process (PARP), which aims to increase the interoperability of the Irish military, the Defence Forces, with other NATO member states and bring them into line with accepted international standards so as to successfully deploy with other professional military forces on peacekeeping operations overseas.

Irish government policy for the deployment of troops to NATO-led missions requires that the missions be mandated by the United Nations (UN Security Council resolution or UN General Assembly resolution), cabinet-backed and approved by Dáil Éireann (the Irish parliament). This is known as Ireland's "triple lock". Ireland supplied a limited number of troops to the NATO-led International Security Assistance Force (ISAF) in Afghanistan (2001–2014) and supports the ongoing NATO-led Kosovo Force (KFOR), as these were sanctioned by UNSC resolutions.

Public opinion in Ireland continues to favour a policy of neutrality in armed conflicts, and currently no major political party fully supports ascension into NATO. There has been, and continues to be, a number of politicians who support Ireland joining NATO, mainly within the centre-right Fine Gael party, but the majority of politicians still do not. It is widely understood that a referendum would have to be held before any changes could be made to neutrality or to joining NATO. Former Secretary General of NATO Anders Fogh Rasmussen said during a visit to the country in 2013 that the "door is open" for Ireland to join NATO at any time.

Malta

When the North Atlantic Treaty was signed in 1949, the Mediterranean island of Malta was a dependent territory of the United Kingdom, one of the treaty's original signatories. As such, the Crown Colony of Malta shared the UK's international memberships, including NATO. Between 1952 and 1965, the headquarters of the Allied Forces Mediterranean was based in the town of Floriana, just outside Malta's capital of Valletta. When Malta gained independence in 1964, prime minister George Borg Olivier wanted the country to join NATO. Olivier was concerned that the presence of the NATO headquarters in Malta, without the security guarantees that NATO membership entailed, made the country a potential target. However, according to a memorandum he prepared at the time he was discouraged from formally submitting a membership application by Deputy Secretary General of NATO James A. Roberts. It was believed that some NATO members, including the United Kingdom, were opposed to Maltese NATO membership. As a result, Olivier considered alternatives, such as seeking associate membership or unilateral security guarantees from NATO, or closing the NATO headquarters in Malta in retaliation. Ultimately, Olivier supported the alliance and signed a defense agreement with the UK for use of Maltese military facilities in exchange for around £2 million a year. This friendly policy changed in 1971, when Dom Mintoff, of the Labour Party, was elected as prime minister. Mintoff supported neutrality as his foreign policy, and the position was later enshrined into the country's constitution in 1974 as an amendment to Article 1. The country joined the Non-Aligned Movement in 1979, at the same time when the British Royal Navy left its base at the Malta Dockyard.

In 1995, under Prime Minister Eddie Fenech Adami of the Nationalist Party, Malta joined the Euro-Atlantic Partnership Council multilateral defense forum and NATO's Partnership for Peace program. When the Labour Party regained power the following year, however, they withdrew Malta from both organizations. Though the Nationalists resumed the majority in parliament in 1998, Malta didn't rejoin the EAPC and PfP programs again until 2008, after the country had joined the European Union in 2004. Since re-joining, Malta has been building its relations with NATO and getting involved in wider projects including the PfP Planning and Review Process and the NATO Science for Peace and Security Program.

NATO membership is not supported by any of the country's political parties, including neither the governing Labour Party nor the opposition Nationalist Party. NATO's secretary-general Jens Stoltenberg has stated that the alliance fully respects Malta's position of neutrality, and put no pressure for the country to join the alliance. Polling done by the island-nation's Ministry of Foreign Affairs found in February 2022 that 63% of those surveyed supported the island's neutrality, and only 6% opposed the policy, with 14% undecided. A Eurobarometer survey in May 2022 found that 75% of Maltese would however support greater military cooperation within the European Union.

Europe

Microstates NATO has diplomatic relations with the 5 European microstates: Andorra, Liechtenstein, Monaco, San Marino, and Vatican City. These microstates are neutral, have only nominal militaries, are surrounded by NATO members (except for Liechtenstein), and are part of the OSCE but do not participate in NATO's PfP.

Liechtenstein has not had an army since 1866. However, the constitution states that the army may be reformed at any time should it be deemed necessary. As of January 2025, there are no plans by the Liechtenstein government to seek NATO membership.

Armenia