Turkey is demanding that Finland and Sweden take concrete steps before it backs their applications to join NATO, while other members of the defence alliance reiterated their support for the Nordic applicants.
Turkey has again made its security concerns clear, presidential advisor Ibrahim Kalin said after a meeting with Finnish and Swedish representatives in Ankara on Wednesday. He said the process could not move forward unless the two countries take specific steps.
Finland and Sweden are applying to join NATO, ending their long-held neutral stance after Russia's invasion of Ukraine altered the European security situation.
However, new members must be agreed unanimously by the countries in the defence alliance and Turkey is blocking Helsinki and Stockholm.
The two Nordic countries should halt propaganda and the financing of "terrorist organizations" such as the banned Kurdistan Workers' Party and the Syrian Kurdish militia YPG, Kalin said.
Turkish security forces often clash with the YPG along the border and in Syria. Ankara believes the group is linked to a wider insurgency.
The United States, by contrast, works closely with the YPG in Syria, considering it a key ally in its fight against the extremist militia Islamic State.
Sweden and Finland, among others, also imposed restrictions on arms exports to Turkey after a Turkish military offensive against the YPG in 2019, angering Ankara. Kalin reiterated Turkish calls for these to be lifted.
Turkey has also complained that both Nordic countries allow operations by the banned Kurdistan Workers' Party (PKK).
Despite Ankara's opposition, German Foreign Minister Annalena Baerbock said that Berlin supported Finland and Sweden's accession to NATO.
"We would welcome Finland and Sweden into our alliance," she said on Wednesday.
Both countries have taken part in NATO for a long time, even if they weren't formal partners, she said in Kristiansand in Norway.
Her Norwegian counterpart Anniken Huitfeldt said it was "very important for Norway, that Sweden and Finland be allowed into NATO." The objections presented by Turkey "can be solved," she said.
One of the reasons that Ankara is insisting that conditions be met is that President Recep Tayyip Erdoğan is performing badly in the polls ahead of an election, with support waning for him and his party.
"He is desperate to score points in foreign policy," Hüseyin Bagci, chairman of the Turkish Foreign Policy Institute, said.
Turkey is due to hold its next elections in 2023, although Erdoğan, could also call an earlier election.