Turkish President Recep Tayyip Erdogan said he won’t allow Sweden and Finland to join NATO because of their stances on Kurdish militants, throwing a wrench into plans to strengthen the western military alliance after Russia’s invasion of Ukraine.

At a news conference in Ankara late Monday, Erdogan poured cold water on expectations that Turkish opposition to the enlargement plan could be easily resolved. The remarks were his clearest indication that he intends to block membership for the two countries, or at least extract concessions for it, since they announced their intentions to join over the weekend.

"These two countries lack a clear stance against terrorism” and "Sweden is a nesting ground for terrorist organizations,” Erdogan said. He also said that Turkey wouldn’t allow countries that impose "sanctions” on Turkey to join NATO, an apparent reference to restrictions on weapons sales imposed by several European nations.