Iran has also been investing in a north-south economic corridor that will link the Caucasus and Russia with the Persian Gulf.
Turkmenistan to supply Turkey with gas via Iran in a new strategic deal.
The government dismisses claims that the arrests are aimed at muzzling dissent and says the judiciary is independent.
Originally built in the 2nd century BCE, it was destroyed by an earthquake in the 3rd century CE and subsequently rebuilt.
The big question now is whether the PKK will actually heed this call by Ocalan and if PKK affiliates will agree.
Zelensky said last week that he saw Turkey as an important security guarantor for Ukraine.
If successful, the move could have wide-ranging implications for the region, while ending a conflict that has killed more than 40,000 people.