Iran can likely build several atomic bombs with its current stockpiles of enriched uranium, the head of the United Nations’ nuclear agency said Thursday.

“They have enough material for several nuclear warheads,” the director general of the International Atomic Energy Agency, Rafael Mariano Grossi, told Bloomberg News Thursday during an interview in Davos, Switzerland.

Iran appears to be storing the enriched uranium, not making it into warheads, Grossi said, while adding that the stockpiling was “not banal.”

Iran is speeding up its uranium enrichment process, and its domestic nuclear industry is now fully independent, even as the country continues to stymie international efforts to monitor its nuclear program.