After a substantial discussion (which notes among other things, the rapid growth of anti-Americanism within the population) Pipes concludes:
The recent transformation has happened so quickly that – formal NATO relations notwithstanding – Turkey can no longer be considered a Western ally. Nor, certainly, is it an enemy. Rather it falls into a middle status – like Russia, China, and Saudi Arabia -- of rival. One day it cooperates, the next it competes. Before long, it may well threaten.
External influences will have limited impact on a Turkey determined to turn Islamist, but existing tools must be fully deployed. Most importantly, an ideologically assertive Turkey must be denied membership in the European Union.