U.N. Secretary-General Guterres’s warning against abandoning nuclear accords came as Iranian Foreign Minister Mohammad Javad Zarif quit his post in a surprise move announced via Instagram Monday. Zarif played a central role in the negotiations leading to the 2015 Iran nuclear deal. Last year, President Trump withdrew from the landmark deal despite international condemnation of the move and U.N. inspectors saying Iran was adhering to the deal. Zarif did not offer any reason for his resignation, writing simply, “I sincerely apologize for the inability to continue serving and for all the shortcomings during my service.”

In a statement released by activists Medea Benjamin and Ann Wright, who met with Zarif hours before his resignation, wrote, “[Zarif] said that when the Iran nuclear agreement was signed in 2015 over 80 percent of the Iranian people supported it, as they hoped it would bring Iran back into the international community and improve their economy. Instead, President Trump quit the agreement and implemented even more sanctions on Iran … Now just 51 percent of Iranians think the nuclear agreement is a good idea because it has brought no economic relief to the Iranian people.”