Pentagon Chief Spokesperson Jonathan Hoffman provided the following readout: 

Acting Secretary of Defense Mark T. Esper met with Hulusi Akar, minister of national defense for Turkey, at the NATO defense ministerial Wednesday.  

The leaders discussed the latest developments in Syria, regional security issues and bilateral relations, including defense cooperation. They reiterated their decades-long commitment as close NATO allies and strategic partners.

Because of this long-standing relationship as allies, the two leaders had a frank and transparent discussion where Secretary Esper reiterated that Turkey's purchase of the Russian S-400 air and missile defense system is incompatible with the F-35 program and that Turkey will not be permitted to have both systems.

The U.S. and Turkey defense leaders reaffirmed their strong, multi-layered and continuous military-to-military relationship and their commitment to the NATO alliance.