Turkey's military buildup on its border with Syria aimed at crushing Kurdish fighters has fueled worries in Iran, which has remained the key regional ally of President Bashar al-Assad during his country's eight-year conflict.

Addressing a Cabinet meeting Oct. 9, just before Turkey launched a military operation into northern Syria, Iranian President Hassan Rouhani called on Turkey, the "brotherly" country, to exercise "patience" and "reconsider" the planned operation.

Turkey views the Kurdish People's Protection Units, the forces operating in northern Syria, as a terrorist entity affiliated with its sworn enemy at home, the Kurdistan Workers Party, which has been battling a bloody war against Ankara since 1984.

In his speech, the Iranian president recognized Turkey's "right" to address its "concerns" about the Syrian border, but he proposed dialogue as the best solution. "The approach adopted today and the backchannel agreements do not benefit the region," he added, without elaborating on those "agreements." Rouhani also advised the Kurdish fighters "to stand by the army of their own country (Syria)."