Hungary remains the only NATO ally not to have ratified Sweden's accession.
Swedish Prime Minister Ulf Kristersson welcomed Turkey's move, saying on X, formerly known as Twitter: "With this, a key milestone has been reached in Sweden's path towards NATO membership."
Turkey's parliament endorsed Sweden's accession in a vote held Tuesday after more than a year-and-a-half of delays that frustrated other allies who argued Sweden's entry would strengthen NATO.
On Thursday, the parliament's endorsement of Sweden's membership and a presidential decree approving its accession protocol were published in Turkey's official gazette, concluding the ratification process in the country.
Welcome Türkiye's approval of the ratification of Sweden's NATO accession. With this, a key milestone has been reached in Sweden's path towards NATO membership.— SwedishPM (@SwedishPM) January 25, 2024
Sweden, along with Finland, abandoned its traditional position of military non-alignment to seek protection under NATO's security umbrella, following Russia's invasion of Ukraine in February 2022.
Finland joined the alliance in April, becoming NATO's 31st member, after Turkey's parliament ratified the Nordic country's bid.
But Turkey held out on approving Sweden's bid, accusing the country of being too lenient toward groups that Ankara regards as security threats.
It sought a series of concessions from Stockholm, including moves to counter Kurdish militants.
Turkey also had been angered by a series of demonstrations by supporters of the outlawed Kurdistan Workers' Party, or PKK, in Sweden as well as Quran-burning protests that roiled Muslim countries.
Turkish President Recep Tayyip Erdogan later also linked the ratification to Turkey's desire to buy fighter jets from the United States.
He has also called on Canada and other NATO allies to lift arms embargoes imposed on Turkey over human rights concerns.
Ankara has requested 40 new F-16 fighter jets as well as kits to modernise its existing fleet.
Sweden, along with Finland, sought NATO membership following Russia's invasion of Ukraine. (AP PHOTO)
US administration officials have said they expect relatively quick action on the F-16 sale after Turkey's ratification.
During the vote on Tuesday, the ruling party said Sweden's tougher stance on Kurdish militants was key to winning approval.
Senior ruling party legislator Fuat Oktay said that Sweden has amended its anti-terrorism laws, curbed the PKK's financial activities, convicted a terrorism suspect and extradited another, and lifted restrictions on arms sales to Turkey.
With Turkey finalising its approval, all eyes have turned on Hungary.
A vote on the protocols for Sweden's NATO accession has not yet appeared on the Hungarian parliament's agenda, and barring a surprise emergency session, the matter is unlikely to go before MPs until at least late February.
Hungarian Prime Minister Viktor Orban says his government is in favour of bringing Sweden into NATO, though he also has suggested that members of his governing Fidesz party remain unconvinced because of "blatant lies" from some Swedish politicians about the state of Hungary's democracy.
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