EU membership in practice ended the country's non-alignment, as it included the adoption of common foreign and security policy and, from 2009 onwards, a mutual defence clause.

The Russian invasion of Ukraine spurred a shift in public opinion, prompting Sweden to apply for NATO membership alongside Finland on 18 May 2022.

Sweden adopted a policy of neutrality following the loss of a large amount of its territory (including Finland) to the Russian Empire during the Napoleonic Wars in 1812.

[4] On 18 September 2007, Prime Minister Fredrik Reinfeldt stated that Swedish membership in NATO would require a "very wide" majority in Parliament, including the Social Democrats, and coordination with Finland.

[14] Sweden has been an active participant in NATO-led missions in Bosnia (IFOR and SFOR), Kosovo (KFOR), Afghanistan (ISAF), and Libya (Operation Unified Protector).

On 1 March 2024, in the wake of Hungary's approval in the National Assembly, the result of a new poll by Verian was released by TV4, showing a record high support for NATO among Swedes from the media outlet, with 66% in favour.

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.

[58] Croatia's president Zoran Milanović stated that his country should block ratification of Sweden'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.

[59] On 28 April 2022, Croatian Foreign Minister Gordan Grlić-Radman announced that Croatia supports Finland and Sweden's applications for membership in NATO.

[154][155] 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 organisations to operate on their territory, 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.

[161] People whom Turkey has requested to be extradited include independent Member of the Swedish Parliament Amineh Kakabaveh for her support of Kurdish organisations,[162] writer and poet Mehmet Sıraç Bilgin (who died in 2015),[163][164] and the Turkish publisher and human rights activist Ragıp Zarakolu.

[183] On 21 May 2022, Andersson, after a phone call with Turkish President Recep Tayyip Erdoğan, told Swedish state television SVT that they were ready for dialogue with Turkey on Sweden's NATO membership.

Jukka Salovaara from Finland, Oscar Stenström from Sweden, İbrahim Kalın and Sedat Önal from Turkey are serving in the memorandum negotiations.

[195] In May, she declared that she would no longer support the governing Swedish Social Democratic Party in important votes in the parliament since she considered parts of the previous agreement had not been followed.

[196] İbrahim Kalın, spokesman for Erdoğan, said that approving Swedish 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.

[201][202] Nationalist Movement Party leader Devlet Bahçeli suggested that a scenario in which Turkey would leave NATO should be considered an option,[203] in which case a new military alliance could be founded.

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

[204] To address Turkey's concerns, in June Sweden pointed to reforms to its anti-terrorism laws which were to come into force on 1 July (although delayed by human rights groups), and announced that it would review its policies on weapons exports to reflect its NATO membership.

[209] While NATO members unanimously agreed to formally invite the countries to join the following day and the accession protocols for Sweden and Finland to join the alliance were signed on 5 July,[210] Erdoğan reiterated his threat to veto their membership, stating that he expected the applicant countries to meet their obligations under the agreement before Turkish parliament would consider approving their accession protocol.

[213] The center-right government formed after the September 2022 Swedish general elections pledged to continue the NATO process, reaffirming a united front with Finland's application, and suggesting that they would be more able to meet Turkish requirements.

[220] In the meantime, Akar said the visit of the Swedish defence chief was cancelled due to the "provocative act, which is clearly a hate crime" citing the permission of burning the Quran.

[225] The third trilateral memorandum meeting took place on 9 March 2023 in Brussels,[226][227] after which Sweden's chief negotiator, Oscar Stenström, stated that membership talks with Turkey would take a long time.

[248] Two days later, Turkey's parliamentary speaker, Numan Kurtulmuş, sent a bill approving Sweden's NATO membership bid to parliament's foreign affairs committee.

On 13 December 2022, Gergely Gulyás, Orbán's chief of staff, stated that parliament would start debating the ratification process of Sweden and Finland's NATO accession on 20 February 2023.

[282] Ágnes Vadai, of Hungarian opposition party Democratic Coalition, expressed a desire to force a vote in the parliament prior to the body's scheduled reconvening in late February.

[283] On 29 January,[284] the opposition parties in Hungary again called for a special session of parliament to vote on ratifying Sweden's application,[285] which was scheduled for 5 February 2024.

[289] Fidesz head Máté Kocsis stated that the ratification could instead occur later in the month during a normal parliamentary session and Orbán encouraged a Swedish delegation to visit Hungary to expedite the process.

[292][293] On 23 February 2024 Kristersson visited Budapest to meet Orbán, and the leaders signed an agreement for Hungary to buy 4 new Saab JAS 39 Gripen C fighter jets from Sweden, improving relations between the two countries.

[304] Sweden's membership facilitates NATO's access to the Baltic states in response to their invasion,[305] which could otherwise be isolated and surrounded by an attack on the Suwałki Gap.