Speaking to reporters in Istanbul on Monday ahead of his departure for a three-day visit to Saudi Arabia, Qatar, and the United Arab Emirates, Erdogan said Turkey has never “shut the door” to discussions with the Syrian government. Turkey has been the biggest military and political ally of the Syrian opposition, which controls the last rebel-held bastion in the country, which is in northwest Syria on the Turkish border.

Ankara has set up dozens of bases and deployed thousands of troops in northern Syria, preventing the Russian-backed Syrian army from re-taking the region. Turkey has also been a base for Syrian opposition groups since 2011. “We can hold a four-party summit [with Syria, Russia, and Iran], and I am also open to a meeting with Assad. What matters here is their approach towards us,” Erdogan told journalists. However, Damascus’s condition of a complete withdrawal of Turkish forces for such a meeting is “unacceptable”, he said.

Erdogan first said this year that he might meet al-Assad as part of a new peace process, but al-Assad said in March that there was no point in a meeting with Erdogan until Turkey’s “illegal occupation” ended. Turkey has said its military operations in Syria have been necessary to secure its southern border. It is trying to remove fighters with the YPG, the Kurdish People’s Defence Units, which Ankara has said is the Syrian branch of the PKK, the Kurdistan Workers’ Party. The PKK has fought a war against the Turkish state since 1984 – a conflict that has led to tens of thousands of deaths.

“We are fighting against terrorism there. How can we withdraw when our country is under continuous threat from terrorists along our border? … We expect a fair approach,” Erdogan said. The defense ministers of Turkey and Syria met late last year for the highest-level talks between the two neighbors since the 2011 Arab Spring uprisings plunged Syria into war and put it and Turkey at odds.