Ukrainian President Volodymyr Zelensky spoke by phone with his Turkish counterpart Recep Tayyip Erdogan on Friday in an attempt to find a way to reinstate the Black Sea Initiative that would allow grain exports to continue, days after Russia withdrew from the agreement.

“Opening the grain corridor is a top priority,” Zelensky said after his phone call with Erdogan. “Together we must prevent a global food crisis,” the president of Ukraine emphasized.

Russia’s withdrawal from the deal led to a renewed naval blockade of Ukrainian ports in the Black Sea on Monday. Moscow also warned that all ships bound for Ukrainian ports would be considered potential carriers of military cargo.

“Because of Russia’s actions, the world is once again on the brink of a food crisis. A total of 400 million people in many African and Asian countries are threatened with starvation,” Zelensky said.

The agreement signed in July 2022, brokered by Turkey and the UN, allowed exports of Ukrainian grain and agricultural products from Black Sea ports. Originally valid for 120 days, it was renewed in November for another 120 days, and in May Russia agreed to extend the agreement by 60 days. On July 17, Moscow suspended its participation, announcing that it would revise its stance if it received guarantees regarding Russian grain and fertilizer exports.