The head of the United Nations’ atomic watchdog traveled Monday to Iran, where his agency faces increasing difficulty in monitoring the Islamic Republic’s rapidly advancing nuclear program as tensions remain high in the wider Middle East over the Israel-Hamas war.

Rafael Mariano Grossi already has warned Tehran has enough uranium enriched to near-weapons-grade levels to make “several” nuclear bombs if it chose to do so. He has acknowledged the agency can’t guarantee that none of Iran’s centrifuges may have been peeled away for clandestine enrichment.

Those challenges now find themselves entangled in attacks between Israel and Iran, with the city of Isfahan apparently coming under Israeli fire in recent weeks despite it being surrounded by sensitive nuclear sites. Grossi is likely to attend an Iranian nuclear conference there while on his two-day trip to Iran.