Turkey's president has warned that Finland and Sweden's entry into NATO would carry security risks for his country and the organisation itself.
“Turkey maintains that the admission of Sweden and Finland entails risks for its own security and the organisation’s future,” President Recep Tayyip Erdogan wrote in an article published by The Economist late Monday.
Erdogan said the activities of the Kurdistan Worker's Party (PKK) are part of the reason why Turkey is objecting to Sweden and Finland joining the defensive alliance.
The PKK has waged a 38-year insurgency against Turkey for Kurdish independence, which has led to tens of thousands of deaths.
It is designated as a terror group by the United States and the European Union, including Sweden and Finland.
However, there has been friction between Ankara and other NATO members over the West's stance towards the PKK's wing in Syria, the People's Protection Units (YPG).
The YPG has played a key role in fighting the Islamic State on the ground in Syria, alongside the US-led coalition.
Referring to the core principle of NATO, which states that all 30 signatories to the treaty must come to the aid of another if it is attacked, Erdogan wrote: “We have every right to expect those countries, which will expect NATO’s second-largest army to come to their defence under Article 5, to prevent the recruitment, fundraising and propaganda activities of the PKK."
Erdogan repeated calls for Finland and Sweden to extradite people Ankara suspects of terrorist activity and to support "the anti-terror operations of NATO members.”
The Scandinavian states both imposed defence export restrictions on Turkey following its 2019 military operation in northeast Syria against the YPG.
In May, Erdogan promised a further cross-border operation to drive the group back from Turkey's borders.
Arms embargoes were “incompatible with the spirit of military partnership," he said.
All NATO member states must approve of Finland and Sweden's bids to join the alliance, which have been driven by Russia’s invasion of Ukraine.
Turkey previously said it will block their accession unless steps are taken, but NATO leaders are hoping to push forward the historic expansion at a summit at the end of June.
In The Economist article, the Turkish president set out Turkey’s role in “arguably the greatest military alliance in history”, while calling for other NATO members to persuade Sweden and Finland to change their positions.
“Where Sweden and Finland stand on the national security concerns and considerations of other countries, with which they would like to be allies, will determine to what extent Turkey would like to be allies with those states,” he added.
Turkey has been a NATO member since 1952.