Die Russen haben bereits zugestimmt, dass die Türkei die Software für die S-400 selber erstellen können und vollen Zugriff auf das System haben werden.
https://www.defenseworld.net/news/24673/Turkish_S_400_Air_Defence_Systems_to_have_Local_Software__Foreign_Minister
"Turkish S-400 Air Defence Systems To Have Local Software: Foreign Minister
The software deployed in the Turkish S-400 Air Defence Systems will have locally developed software and will operate with unique radar, detection and surveillance systems.
Turkish Foreign minister Mevlut Cavusoglu said today that the system will be programmed in such a way as not to detect NATO systems as hostile.
“The S-400s will be based on domestic software and will operate with unique radar, detection and surveillance systems. So they would constitute no threat to NATO systems or see them as the enemy,” he said."