Turkey’s President Recep Tayyip Erdogan kicked off a high-profile visit to Iran today as both countries vowed to prevent Iraq’s Kurds from splitting away to form their own independent state and to boost economic ties.

Erdogan was flanked by his top lieutenants including Foreign Minister Mevlut Cavusoglu, Defense Minister Nurettin Canikli, Interior Minister Suleyman Soylu and his son-in-law, Energy Minister Berat Albayrak.

Turkey’s Chief of General Staff Hulusi Akar, who has been in Tehran since Sunday holding talks on cooperation in Iraq and Syria, was among those to receive the Turkish leader at the airport.

At a joint news conference with his Iranian counterpart Hassan Rouhani, Erdogan repeated Turkey’s demands that the Kurdistan Regional Government (KRG) annul the results of the referendum on Kurdish independence that was held and overwhelmingly approved on Sept. 25. “There is no country other than Israel that recognizes it. A referendum that was conducted by sitting side by side with [Israel’s national spy agency] Mossad has no legitimacy,” he said. Erdogan warned of further “decisive steps” that Turkey, Iran and Baghdad might take if the KRG ignores their calls.