The government of Turkey does not support Finland and Sweden joining NATO, Turkish President Recep Tayyip Erdoğan said Friday. 

“We are following the developments regarding Sweden and Finland, but we are not of a favorable opinion,” Erdoğan said in Instanbul, per The Associated Press.

“Scandinavian countries are guesthouses for terrorist organizations,” he added, per Reuters. “They are even members of the parliament in some countries. It is not possible for us to be in favor.”

Erdoğan’s comments throw a potentially huge wrench in both Finland and Sweden’s possible membership, considering all 30 NATO allies must approve a candidate country’s application. Sweden has not yet made final its intention to apply, though a decision is expected soon. Finland announced its plans to move forward with accession on Thursday.

The remarks are also at odds with those made by NATO Secretary-General Jens Stoltenberg, who previously said Finland and Sweden would be welcomed to the military alliance with open arms.

Turkey’s opposition pertains to its issues with “Sweden and other Scandinavian countries’ alleged support for Kurdish militants and others whom Turkey considers to be terrorists,” AP writes. Erdoğan also said he did not want to repeat a “mistake” similar to when Turkey agreed to readmit Greece to NATO’s military wing in 1980, allowing Greece to “to take an attitude against Turkey.”

Erdoğan did not, however, explicity state his intention to outright block an accession attempt from either country, AP notes.