Over the past decade or so, Turkey, a critical NATO member and once-aspiring candidate for membership in the European Union, has refashioned itself as a revisionist power openly challenging not just its regional neighbors but also treaty allies like France and the United States.

Currently, Turkey’s military—NATO’s largest after the U.S.—is actively involved in a number of theaters, including Syria, Iraq, the South Caucasus, Libya and the Eastern Mediterranean, with the intention to either steer the outcome of a dispute in its favor or alter the existing order. This behavior represents a radical change from Turkey’s earlier predilection for a foreign policy that embraced the status quo and that mostly eschewed foreign adventures. ...