Not a good sign
Turkey has said since last December it intended to buy the S-400, a sale that worried NATO members because the system is not interoperable with its defense systems, including the F-35. Turkey is a partner in the U.S.-led Joint Strike Fighter program to build the F-35, of which Ankara intends to buy
The S-400 could also provide a way to steal F-35 technology should the aircraft be synced with it, officials feared.
Turkey has not indicated whether it would give up on the S-400 sale.
Washington and Ankara have also tangled over U.S.-backed Kurdish forces in Syria.
https://thehill.com/policy/defense/422173-state-department…
The State Department has approved a possible deal to sell Turkey a Patriot air and missile defense system, potentially worth up to $3.5 billion, officials told Congress on Tuesday.