Sweden is closer than ever to becoming a Nato member – but its accession to the western military alliance, which has faced delays for more than a year, is still not a done deal. Russia’s full-scale invasion of Ukraine two years ago prompted Sweden and Finland to shift long-held security policies, and the two countries applied to join Nato in May 2022. At the time, Nato accession for both was expected to be a quick process, given their advanced militaries, high level of interoperability with alliance forces and status as EU members. Nevertheless, they faced obstacles to accession. Finland joined the alliance in April 2023, but Sweden’s accession has yet to be completed. On Tuesday, Turkey’s parliament ratified Swedish membership, putting the country a step closer to accession – but it is still awaiting the Turkish president Recep Tayyip Erdoğan’s final signature. Hungary’s parliament has yet to ratify, and delays could continue. What is Nato? The North Atlantic Treaty Organization (Nato), a collective defence alliance, was founded in 1949. Over the years, the alliance has grown from its 12 founding members to a total of 31. It operates under the powerful principle, outlined in its founding treaty, that an armed attack against one or more Nato members “shall be considered an attack against them all”. During the cold war, Nato focused heavily on deterrence and defence. After the fall of the Soviet Union, the alliance expanded eastward. The Baltic countries and central European states such as Poland and Hungary joined the alliance. The alliance became involved in operations beyond its borders, for example leading peacekeeping forces in Kosovo. But Russia’s invasion of Ukraine contributed to another shift in its focus, as military planners now put an emphasis on bolstering the alliance’s defences. Why is Sweden’s accession taking so long? While all Nato countries agreed Sweden and Finland should become members of the alliance, Turkey raised concerns, in particular about the activities of Kurdish groups and restrictions on arms exports to Turkey. As a result, in June 2022, the three countries signed a joint memorandum outlining steps they would take to address Ankara’s qualms, and in return Turkey said it would support inviting Sweden and Finland to become Nato members. But while most Nato countries quickly ratified Sweden and Finland’s membership, Turkey and Hungary dragged out the process. They ultimately signed off on Finnish membership, but kept Sweden waiting. During July’s Nato summit in Vilnius, Erdoğan vowed to send Sweden’s ratification to parliament as the two countries confirmed that they had “worked closely together to address Türkiye’s legitimate security concerns” and “as part of that process, Sweden has amended its constitution, changed its laws, significantly expanded its counter-terrorism cooperation against the PKK, and resumed arms exports to Türkiye”. But further delays ensued. Turkey’s leadership has used the accession as a negotiating chip, including in its quest to get approval to buy American F-16 fighter jets. On Tuesday, Turkey’s parliament finally voted in favour of Swedish membership, and Erdoğan is expected to sign the legislation in the coming days. That leaves only Hungary’s parliament, which has yet to ratify. Why is Hungary dragging its feet? Hungary’s leadership has not provided a clear reason for delays. Domestically, senior politicians from the ruling Fidesz party have argued that the delay is due to Swedish criticism of the state of Hungarian democracy. Formally, Hungary has not put forward any substantive objections at Nato to Swedish membership. Unlike Ankara, which held highly structured negotiations with Finland and Sweden, Budapest has not made any concrete demands. Hungary is an outlier in the western defensive alliance: while it remains an active Nato member, senior Hungarian officials still routinely meet their Russian counterparts and are often publicly critical of western policies toward Moscow. Within Nato, the Hungarian delay in ratifying Sweden’s membership has long been interpreted in the context of a close alliance between Hungary’s prime minister, Viktor Orbán, and Erdoğan. Faced with mounting political pressure and increasingly isolated, Orbán said on Wednesday that he had spoken on the phone with the alliance’s secretary general, Jens Stoltenberg. “I reaffirmed that the Hungarian government supports the Nato membership of Sweden. I also stressed that we will continue to urge the Hungarian national assembly to vote in favour of Sweden’s accession and conclude the ratification at the first possible opportunity,” he said. Stoltenberg said he had a “good call” with Orbán. “I welcome the clear support of the prime minister and his government for Sweden’s Nato membership. I look forward to the ratification as soon as parliament reconvenes,” he said. Why is Sweden’s accession so important to Nato? The accession of Sweden and Finland is of high strategic value to Nato. The two countries’ geographic location significantly bolsters the alliance’s position in the north, turning the Baltic Sea into a de facto Nato lake. Sweden and Finland also bring advanced military capabilities to the alliance. This week, Nato is launching exercise Steadfast Defender 2024 – its largest exercise in decades, involving approximately 90,000 forces from 31 Nato countries and Sweden. Expansion northward also has symbolic value. “President Putin wanted less Nato, he is getting more Nato – and that’s an important message,” Stoltenberg said of Swedish and Finnish accession. What are the Swedes saying? Sweden’s leadership has insisted that it is ready for Nato membership. Reacting to the vote in Turkey’s parliament, the Swedish prime minister, Ulf Kristersson, said: “Today we are one step closer to becoming a full member of Nato,” adding that it was “positive” that the parliament had signed off. Orbán this week publicly invited Kristersson to Hungary for talks, but Swedish officials have taken a cautious approach. The country’s foreign minister, Tobias Billström, said that before responding the government would need to “think through what the letter signals”. How are Nato allies responding? Within the alliance, there is growing frustration with Hungary. One senior European diplomat, who spoke on condition of anonymity to discuss sensitive Nato matters, said: “We are shocked. Hungary always consistently assured us that they will not be the last.. “We frankly do not understand what is going on.” A second senior European diplomat said that “after good news from Ankara, all attention goes to Budapest”. “It is normal among democratic nations to voice out healthy criticism, but it is not normal to diminish security of all allies without substantive reasons,” they added.