The US has halted supply of equipment related to the stealthy F-35 fighter jet to Turkey, Reuters reported.

As it was noted the US officials told their Turkish counterparts they will not receive further shipments of F-35 related equipment needed to prepare for the arrival of the stealthy jet.
Turkey produces some parts for the fighter.  In Turkey, produced some parts for the fighter: parts of the fuselage, chassis and cockpit displays.

Washington took this step because of the purchase of Russian S-400 air defense systems. 
The United States and other NATO allies fear the radar on S-400 would enable Russia to learn how to spot and track the $90 million (€80 million) stealth jet.

On March 28, US senators introduced a bipartisan bill to prohibit the transfer of F-35 fighter aircraft to Turkey until the US government certifies that Ankara will not take delivery of a Russian S-400 air defense system.

F-35 is the fifth-generation combat aircraft. The F-35 first flew on 15 December 2006.