NATO chief Jens Stoltenberg said on Monday that Turkey has agreed to back Sweden’s bid to join the military alliance – a major development on the eve of the NATO summit. The announcement epresents a stunning about-face from Turkish President Recep Tayyip Erdoğan, who had earlier on Monday suggested Sweden could only join the alliance after his country is accepted into the European Union. Erdoğan has stood in the path of Sweden joining NATO for more than a year over a multitude of concerns. Speaking at a news conference in Vilnius, Lithuania, following a meeting with Erdoğan and Swedish Prime Minister Ulf Kristersson, Stoltenberg said that the Turkish president “has agreed to forward the accession protocol for Sweden to the Grand National Assembly as soon as possible, and work closely with the Assembly to ensure ratification.” Erdoğan dropping his opposition marks a major step forward, but does not mean that Sweden will immediately become the next member of the alliance. Stoltenberg did not offer a specific timeline for when Erdoğan would move the document forward to the Turkish Parliament, which must then vote to approve it. Hungary also has not voted to approve Sweden’s membership, though Stoltenberg said Monday that Hungary had made clear that it would not be the last to ratify Sweden’s bid. Asked by a reporter when Sweden can be expected to officially become a NATO member, Stoltenberg was unwilling to commit to an answer, saying that it was up to Turkey to make an announcement and preferred to focus on the merits of a “historic day”. “I think that we have to respect that every parliament has their own integrity, their own timelines, so I welcome that the president has made this clear that he will work with the parliament to ensure ratification, but exactly when has to be announced by the Turkish parliament,” Stoltenberg said, adding that the move was the result of a year of negotiations. The movement on NATO’s accession comes after months of opposition and demands from Ankara. Turkey claimed that Sweden allows members of recognized Kurdish terror groups to operate, most notably the militant Kurdistan Workers’ Party (PKK). Turkey had also accused Swedish officials of complicity in Islamophobic demonstrations, such as the burning of the Quran. At his news conference Monday, Stoltenberg noted that Sweden and Turkey had “worked closely together to address Turkey’s legitimate security concerns.” “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 Turkey,” he said. NATO said in a statement that there were additional commitments made at the meeting between Stoltenberg, Erdogan and Kristersson. The two countries agreed to continue cooperation on counter-terrorism efforts, and NATO will establish a new Special Coordinator for Counter-Terrorism role, the statement said. Sweden and Turkey “also agreed to step up economic cooperation.” In addition, Sweden “will actively support efforts to reinvigorate Türkiye’s EU accession process,” the statement said. US President Joe Biden, who is scheduled to meet with Erdoğan on Tuesday evening, welcomed the Turkish president’s commitment “to transmit the Accession Protocol for Sweden to Türkiye’s Grand National Assembly for swift ratification.” “I stand ready to work with President Erdoğan and Türkiye on enhancing defense and deterrence in the Euro-Atlantic area,” Biden said in a statement Monday. Top US officials had stepped up pressure on their counterparts in Ankara in the days leading up to the NATO summit. Biden spoke with Erdoğan while he was flying aboard Air Force One Sunday. US national security adviser Jake Sullivan spoke with officials in Turkey and Sweden, respectively, on Monday in preparation for the summit. US Secretary of State Antony Blinken spoke with Turkish Foreign Minister Hakan Fidan three times in a matter of five days, including on Monday morning. The news represents a major win for Biden, who had consistently expressed confidence that Sweden would join the alliance at the Vilnius summit, despite Turkish opposition. The president told CNN’s Fareed Zakaria in an exclusive interview ahead of the summit that he was optimistic that Sweden would eventually be admitted to NATO, noting Turkey is seeking to modernize its F-16 fleet, along with Greece, which has voted to admit Sweden. “Turkey is looking for modernization of F-16 aircraft. And (Greek Prime Minister Kyriakos) Mitsotakis in Greece is also looking for some help,” Biden said. “And so, what I’m trying to, quite frankly, put together is a little bit of a consortium here, where we’re strengthening NATO in terms of military capacity of both Greece as well as Turkey, and allow Sweden to come in. But it’s in play. It’s not done.” This story has been updated with additional reporting.