VIENNA (AP) — The head of the International Atomic Energy Agency is set for another four-year term at the helm of the U.N. nuclear watchdog as it grapples with monitoring Iran’s nuclear activities and tries to shore up the safety of power plants in Ukraine.

The IAEA said that its 35-nation board of governors on Friday reappointed Argentine diplomat Rafael Mariano Grossi by acclamation for a second term as the organization’s director-general, beginning in early December.

The annual meeting of the IAEA’s 176 member countries, the general conference, will have to sign off formally on the reappointment when it meets in September.

Grossi said in a statement that he was “deeply honored” by the board’s unanimous decision.

“It comes at a time when we face many major challenges and I’m fully committed to continue to do everything in my power to implement the IAEA’s crucial mission in support of global peace and development,” he said.

Grossi took charge of the Vienna-based agency in December 2019, months after his predecessor, Yukiya Amano, died in office.

His time in office has come amid mounting tensions between Iran and the West as Tehran’s 2015 nuclear deal with world powers unraveled. The IAEA has sought to keep up its monitoring of Iran’s nuclear activities amid mounting difficulties.

Over the past year, Grossi has repeatedly expressed alarm about the risks of a nuclear disaster following Russia’s invasion of Ukraine, which has seen Moscow’s forces occupy the Zaporizhzhia nuclear plant — Europe’s biggest.

The IAEA has placed teams of experts at all four of Ukraine’s nuclear power plants, including Zaporizhzhia.

Grossi has for months pursued a delicate diplomatic drive to get a “nuclear safety and security protection zone” set up around the Zaporizhzhia plant, an aim that so far has proven elusive.