Madrid, 29 June 2022 (dpa/MIA) - NATO has officially started the process of admitting Sweden and Finland into the alliance, with all 30 leaders in favour, including Turkish President Recep Tayyip Erdoğan, who had held up their accession for weeks. Turkey dropped its opposition to the Nordic countries' membership application in a last-minute deal ahead of the start of the NATO summit in Madrid on Wednesday. The meeting is an annual showcase for the Western alliance to put on a united front. The wrangling between Ankara and the other members over Sweden and Finland's fate had threatened the show of solidarity, especially as NATO tries to adapt to confront the threat from Russia. "Today, NATO leaders took the historic decision to invite Finland and Sweden to become members of NATO," Secretary General Jens Stoltenberg told reporters. Stoltenberg said it required "hard work over many weeks" but that talks Tuesday night between Erdoğan, Finnish President Sauli Niinistö and Swedish Prime Minister Magdalena Andersson had broken the deadlock. Shaken by the Russian invasion of Ukraine, Sweden and Finland applied to join NATO on May 18. Turkey however blocked their bid for weeks over concerns linked to terrorism. New NATO membership requires unanimity. A breakthrough was secured after the three leaders agreed to cooperate in a series of counterterrorism efforts. Ankara had accused both countries of supporting the Kurdistan Workers' Party (PKK) and the YPG, a Kurdish militia based in Syria, both of which Turkey classifies as terrorist groups. Both countries disputed the charges. Turkey also demanded the extradition of several suspects. To get Ankara to drop its opposition, Sweden and Finland pledged that there would be no arms embargoes against Turkey. In addition, they promised decisive action against Kudish terrorists and the swift consideration of Turkish requests for the extradition of terrorist suspects. Turkish Justice Minister Bekir Bozdağ said on Wednesday that Sweden and Finland are expected to extradite 33 "terrorists" under the trilateral deal. "We will ask them to live up to their promises," Bozdağ said. "This is a quite a significant win for Ankara," said Soner Çağaptay of the US foreign policy think tank Washington Institute. "This is the first time two prospective NATO allies have committed to not helping the YPG," Çağaptay told dpa, referring to the US-backed Syrian Kurdish militia whom Ankara labels terrorists. "Turkey is eventually pining for having other allies make similar commitments in order to disengage the White House policy on YPG," he added. According to plans, the accession protocols are to be signed next Tuesday. After that, they still have to be ratified by all NATO member states, a process that is expected to take up eight months. Germany, for instance, must get the approval of parliament. A spokesman for the Foreign Ministry in Berlin said the decision-making process would "go even faster than you and I usually think is possible."