A diplomatic sparring match has erupted between the United States and Turkey, testing the boundaries of an already unsteady alliance. The U.S. Embassy in Ankara announced on Oct. 8 that it was suspending all nonimmigrant visa services until it could "reassess" the commitment of the Turkish government to the security of U.S. personnel. Hours later, the Turkish Embassy in Washington issued a similar statement, declaring it would no longer process any nonimmigrant visas for U.S. citizens to Turkey. The retaliatory measures come as bitterness simmers over Turkish government requests to extradite Gulen in exchange for an American pastor held in Turkey since Oct. 2016 — and U.S. refusals to comply. More important, Turkey has long been critical of U.S. support for Kurdish militant groups battling the Islamic State in Syria and Iraq.