It’s not every day that NATO fights among itself. But the alliance is in the midst of a lingering argument that won’t go away. The issue: Sweden and Finland’s incorporation into NATO.

The dispute pits most of the alliance against Turkey, one of the 33 oldest members. The arguments rest less on whether Finland and Sweden would contribute to NATO’s collective defense and more on what Turkey considers slow implementation of a deal reached in June. That deal saw the two Nordic countries promising to review Ankara’s extradition requests of accused Kurdish militants living on their soil. The Biden administration has been urging Turkey to lift its demands ever since. In the U.S. view, Finland and Sweden are already de facto NATO members; the Senate approved the accession protocols in August in a resounding 95-1 vote.