The head of the International Atomic Energy Agency said Monday that the U.N. nuclear watchdog’s long-awaited expert mission to the Zaporizhzhia power plant in Ukraine “is now on its way.” IAEA director general Rafael Grossi has long sought access to the Zaporizhzhia plant, Ukraine’s and Europe’s biggest, which Russian forces have controlled since soon after the war began. “The day has come,” Grossi wrote on Twiter, adding that the Vienna-based IAEA’s “Support and Assistance Mission ... is now on its way.” “We must protect the safety and security of #Ukraine’s and Europe’s biggest nuclear facility,” he wrote. “Proud to lead this mission which will be in #ZNPP later this week.” Grossi posted a picture of himself with 13 other experts. Read:Ukraine, Russia trade more blame on threats to nuclear plant Russia and Ukraine have traded claims of strikes at or near the plant in recent days, intensifying fears that the fighting could cause a massive radiation leak.