Turkey wants to rejoin the

F-35 programme

In his telephone conversation with US President Donald Trump, President Erdoğan stated that steps are expected from the US in the new period in the fight against terrorism with an understanding that respects Turkey's interests, and that in order to improve the cooperation of the two countries in the field of defence industry, it is necessary to end CAATSA sanctions, finalise the F-16 procurement process and finalise the issues of Turkey's re-accession to the F-35 programme.
This is nothing new and is the Turkish position for years, but still.
F-35 might be problematic for a country that would only operate one type, like say Denmark, but not for us. For us, there's only the positives, in a world where HvKK operates F-16 Özgürs, Vipers, Eurofighters, Kaans and F-35s. It would also make us the largest and most capable air force in our region, easily.
F-35 brings unmatched capability. Kaan for example isn't planned to have the same level of sensor fusion F-35 has.
Using F-35 makes it easier to implement designing, building and operating advanced fighter aircraft, as we've seen in the case of building Kaan.
And operating F-35 means we would have more options on how to fight against another F-35s as we would know its capabilities first hand.
Very simple...
Moreso regardless, Eurofighter procurement must continue as planned. We must never again be stuck with one supplier. A HvKK with 40 F-35s, 40 Eurofighters and 40 Kaans by 2035 would make it the prime air force in the region.