Following the war, foreign policy was guided by the Paasikivi–Kekkonen doctrine, which aimed to ensure Finland's survival as an independent sovereign, democratic, and capitalist state next to the Communist Soviet Union.

As a result, Finland took neutral stances to stay out of great power conflicts, and refrained from joining NATO, the European Communities, or other institutions which were established following the war by the Western democratic states, as well as the Soviet-led Warsaw Pact.

[7] During the peak of the Cold War, the Finnish government made a conscious effort to increase defence capabilities to ensure a strong deterrent for any potential invasion.

From 1968 onward, the Finnish government adopted the doctrine of territorial defence, which requires the use of large land areas to delay and wear out a potential aggressor.

The government preferred to wait until after the negotiations of the new EU treaty were concluded before reviewing their policy on NATO, to determine if it included a new EU-level defence agreement.

[11] Finnish think tank EVA [fi], which has regularly commissioned opinion polls on NATO membership, noted in its 2015 report a downward trend in the percent opposed that started in 1998, including a steep decline after the 2012 presidential election.

[10] The Finnish government's 1997 defense white paper strongly advocated the development of interoperability to support international crisis management in line with the PfP concept.

[26] On 25 February, a Russian Foreign Ministry spokesperson threatened Finland and Sweden with "military and political consequences" if they attempted to join NATO.

[27] Following a meeting on 1 March 2022 to discuss whether to apply to become full members of NATO, Prime Minister Sanna Marin stated that no decision had been made on the issue yet, saying that "such an important question needs to be dealt with thoroughly".

[28] According to news reports from early March 2022, Finland and Sweden had begun plans to apply for Major non-NATO ally status with the United States.

[47] Two other former presidents from the Social Democratic Party, Tarja Halonen and Mauno Koivisto, have publicly opposed the idea, arguing that NATO membership would deteriorate Finland's relations with Russia.

[54] He has said that "Finnish membership would make NATO stronger", identifying the country's military capability and commitment to remaining a democratic society as assets.

[64] According to Hanna Smith [fi], Director of Research at the European Centre of Excellence for Countering Hybrid Threats, the rapidity of Finnish movement into NATO has surprised Russia.

She predicted that Russia will begin a hybrid campaign to influence the Finnish decision process, including cyber attacks, with increasing escalation if Finland moves closer to membership.

On 12 May 2022, Finnish president Sauli Niinistö and prime minister Sanna Marin announced in a joint press conference that they were in favour of seeking NATO membership "without delay".

[136] On 15 May 2022, Niinistö and Marin announced that the president and Ministerial Committee on Foreign and Security Policy had adopted a report endorsing Finland joining NATO, beginning the formal constitutional process of applying.

[55] With negotiations concluded and a reconfirmation of the applicant's intent to join, the accession protocol needed ratification by all the existing NATO member states;[142] this was estimated to take between four months and a year.

[149] Croatia's president Zoran Milanović stated that his country should block ratification of Finland's accession until electoral reform measures are implemented in neighbouring Bosnia and Herzegovina, though the Foreign Minister expressed the government's support for any application.

[152] Turkish president Recep Tayyip Erdoğan voiced his opposition to Finland and Sweden joining NATO, saying that it would be "impossible" for Turkey to support their application while the two countries allow groups which Turkey classifies as terrorist organizations, including the Kurdish militant groups Kurdistan Workers' Party (PKK), Kurdistan Communities Union (KCK), Democratic Union Party (Syria) (PYD), and People's Defense Units (YPG) and the supporters of Fethullah Gülen, a US-based Muslim cleric accused by Turkey of orchestrating a failed 2016 Turkish coup d'état attempt, to operate on their territory.

)[155] Turkey requested the extradition of alleged PKK members from the Nordic countries and demanded the arms embargo imposed by the Finnish and Swedish governments in response to its 2019 Turkish offensive into north-eastern Syria against the YPG be lifted.

[164] On the same day, Finnish President Sauli Niinistö and Former Swedish Prime Minister Magdalena Andersson announced that they were always ready for talks with Turkey and always condemned terrorism.

[178] Speaking later, İbrahim Kalın, spokesman for Erdoğan, said that approving Finnish membership was not being ruled out, but that the status of these groups was "a matter of national security for Turkey" and that negotiation would be required.

Canadian Foreign Minister Mélanie Joly also held talks with Turkey to convince the Turkish government of the need for the two Nordic nations' integration.

[186][187] Nationalist Movement Party leader Devlet Bahçeli suggested that a scenario in which Turkey would leave NATO should be considered an option,[188] in which case a new military alliance could be founded.

[189] In late May 2022, opposition leader Kemal Kılıçdaroğlu argued that in case the accession row persisted and AKP and MHP decided to close the Inçirlik Air Base, the CHP would support this.

[195] However, Erdogan reiterated his threat to veto their membership, stating that he expected the applicant countries to meet their obligations under the agreement before the Turkish Grand National Assembly would consider approving their accession protocol.

[201][202] On 26 August 2022, Jukka Salovaara, chief negotiator responsible for Finland's NATO membership, said in a statement after the tripartite memorandum meeting in Vantaa that they are in deep consensus with Turkey.

[212][213] On 29 January 2023, Turkish President Recep Tayyip Erdoğan announced that he had requested the extradition of 130 suspected individuals in order for Finland and Sweden to be approved for NATO membership.

[239][240] On 4 April 2023, Turkish Foreign Minister Mevlüt Çavuşoğlu delivered the document of approval for Finland's participation to U.S. Secretary of State Antony Blinken in Brussels.

[320] On 7 March 2024, Stubb made his first foreign trip as Finland's new president to NATO's Nordic Response military exercise in northern Norway.