Turkey’s president highlighted the activities of the Kurdistan Workers’ Party as part of his country’s objections to Sweden and Finland joining NATO and said both nations doing so would carry security risks for Turkey.

The group known as PKK has waged a 38-year insurgency against Turkey that has led to tens of thousands of deaths. It is designated a terrorist entity by the United States and the European Union, including Sweden and Finland.

However, the West’s attitude to the PKK’s Syrian wing, the People’s Protection Units, or YPG, has caused acrimony between Ankara and other NATO members. The YPG forms the backbone of the forces involved in the U.S.-led fight against the Islamic State group.

"Turkey maintains that the admission of Sweden and Finland entails risks for its own security and the organization’s future," President Recep Tayyip Erdogan wrote in an article published by The Economist late Monday.

Turkey's President Recep Tayyip Erdogan

Turkey's President Recep Tayyip Erdogan speaks during a news conference, in Ankara, Turkey, on May 14. (AP Photo/Burhan Ozbilici)

TURKEY'S ERDOGAN ACCUSES SWEDEN AND FINLAND OF SUPPORTING TERRORISM, POTENTIALLY THWARTING NATO ASPIRATIONS

Referring to the central tenet of NATO’s mutual defense policy, he added: "We have every right to expect those countries, which will expect NATO’s second-largest army to come to their defense under Article 5, to prevent the recruitment, fundraising and propaganda activities of the PKK."

Turkish President Erdogan has made it clear that his country won't be supporting Finland and Sweden's application to join NATO

Turkey's President Tayyip Erdogan holds a news conference during the NATO summit at the alliance's headquarters in Brussels, Belgium, on June 14, 2021. (Reuters/Yves Herman/Pool/File Photo)

All NATO members must approve the two Nordic nations’ bids to join the alliance, which were propelled by Russia’s invasion of Ukraine. Turkey has said it won’t allow their accession unless steps are taken, but NATO leaders are looking to the NATO summit in Spain in late June as the chance for the historic expansion.

Erdogan reiterated calls for Finland and Sweden to extradite people Ankara suspects of terrorist activity and to support "the anti-terror operations of NATO members."

He also said arms embargoes were "incompatible with the spirit of military partnership."

SWEDEN, FINLAND NATO BID: OFFICIALS TRAVEL TO TURKEY IN PUSH TO OVERCOME THEIR OBJECTIONS

NATO Secretary-General Jens Stoltenberg in Brussels to discuss Sweden and Finland NATO applications

NATO Secretary-General Jens Stoltenberg displays documents as Sweden and Finland applied for membership in Brussels, Belgium, May 18. (AP/Johanna Geron)

Sweden and Finland were among countries to impose defense export restrictions on Turkey following its 2019 incursion into northeast Syria that aimed to drive back the YPG. In recent days, Erdogan has promised a further cross-border operation against the group.

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The president set out Turkey’s role in "arguably the greatest military alliance in history" since it joined in 1952 and called 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.