The Latest: US aware Turkey taking Russian missile system

The acting U.S. secretary of defense says Washington is aware that Turkey has begun taking delivery of a Russian-made S-400 air defense system.Mark Esper, who is expected to be officially nominated next week to be defense secretary, told reporters at the Pentagon that the U.S. remains unwilling to allow Turkey to acquire the U.S. F-35 stealth fighter, as long as it has the S-400.The Trump administration has repeatedly told Turkey that it will be cut off from the F-35 fighter program if it buys R