Turkey has criticized U.S. Secretary of State John Kerry for suggesting that negotiations would have to be opened with President Bashar al-Assad to end the conflict in Syria.

Foreign Minister Mevlüt Çavusoğlu told Turkey’s state-run Anatolia news agency Monday that all Syria’s current problems, on the fourth anniversary of the start of the uprising in March 2011, were caused by Assad’s government.

“What is there to be negotiated with Assad?” Çavusoğlu was quoted as saying at the end of his visit to Cambodia.

“You are going to have what [kind of] negotiations with a regime that has killed over 200,000 people and has used chemical weapons?” he asked. “Up until now, what result has been reached [with the regime] through negotiations?”

Instead, he said all parties needed to work for a political “transformation” in Syria.

In an interview with CBS over the weekend, Kerry conceded that “we have to negotiate in the end” with Assad.