During his testimony in front of the House of Representatives’ Appropriations Committee on 1 May, US Acting Defense Secretary Patrick Shanahan has confirmed that Turkey won’t be able to get its hands on F-35 stealth aircraft if it proceeds with its intended purchase of Russian-made S-400 surface-to-air missile systems.

"I think there’s very little possibility that they have a misunderstanding," Shanahan said when Rep. Diaz-Balart inquired whether this message has been sent to Ankara "clear enough", and if there’s any chance that Turkish government hasn’t understood the message.

Diaz-Balart also stressed that "it’s one or the other – they cannot have the F-35", to which Shanahan replied that "there’s no confusion on our part". 

Earlier this week, Turkish President Recep Tayyip Erdogan claimed that a multinational project on the development of the F-35 Lightning II would collapse without Turkey’s participation.

Washington has repeatedly voiced concerns that if Turkey acquires both S-400s and F-35s, it will create a possible security risk as Russian experts would allegedly be able to obtain key insights into sensitive information related to the warplane's technology.

Ankara, for its part, has maintained that the S-400s were not connected to the security of NATO, the US or the F-35 in any way. Despite Ankara's explanation of the issue, Washington has decided to stop deliveries of F-35 fighter jet parts to Turkey.