Turkey to give 'appropriate' response to US letter - Kalin

US acting defence secretary's letter to Turkey’s defence chief over F-35 fighter training programme is "against the spirit of alliance" and an "appropriate" response will be given, Turkish presidential spokesman Ibrahim Kalin said on Thursday. 

He said that he has discussed the letter with US National Security Advisor John Bolton.

The letter sent last week said that Washington was cutting short a F-35 fighter jet training programme for Turkish pilots over “safety concerns.”      

Kalin said the US's attitude on Ankara's purchase of Russian S-400 air missile system would permanently harm bilateral relations and expressed hope that the US would give up this attitude.

Tensions between the US and Turkey have simmered over Ankara’s purchase of Russian S-400 defence systems.

Washington claims the purchase will jeopardise Turkey's role in the F-35 fighter jet programme and has threatened sanctions.

Turkey has said there is no conflict between the S-400 and the F-35 and has called for a working group to clarify the issue.    

Talking about Turkey's security situation, Kalin said that the possibility of the formation of a PKK state on the Turkish-Syrian border is out of question.

"Thanks to skilful leadership of our president, a PKK state, which was attempted to be established on the Turkish-Syrian border, is out of the question now," Kalin said after a Cabinet meeting in capital Ankara.

In its more than 30-year terror campaign against Turkey, the PKK — listed as a terrorist organisation by Turkey, the US and the EU — has been responsible for the deaths of nearly 40,000 people, including women and children. 

The PYD/YPG is the PKK's Syrian branch, and also works under the label of the SDF.