Step 1: What is asked.
We need the country that developed the Yildirimhan missile, shown first at SAHA 2026.
Step 2: About SAHA Expo.
SAHA Expo is a defence show where countries display their latest aerospace and weapon technology.
Step 3: The missile.
The Yildirimhan missile was a major highlight at the 2026 SAHA Expo.
Step 4: The developer.
The name itself is Turkish, and the missile is part of Turkey's home grown defence program.
Step 5: Remove others.
Iran, Israel, and Russia are not the makers of this missile.
Step 6: Conclusion.
So the country is Turkey.
Answer: Turkey