ERBIL, Iraq — Hailing the American strikes on Iran as a success, President Donald Trump said late Saturday that the Islamic Republic’s key nuclear sites were “completely and fully obliterated.”

But despite his bullish claims, the extent of the damage to the deeply buried facility at Fordo, as well as sites at Isfahan and Natanz, is unclear and almost 400 kilograms, or 880 pounds, of uranium enriched to 60% is publicly unaccounted for. Power plants require the radioactive metal to be enriched to only 3%-5%, whereas 90% is required to build a nuclear warhead.

Speaking to the United Nations Security Council on Sunday, Rafael Mariano Grossi, the director general of the U.N.’s nuclear watchdog, said damage was visible at the Fordo and Natanz sites after American B-2 Spirit bombers dropped 14 GBU-57 Massive Ordnance Penetrator munitions known as “bunker busters” on them and U.S. Tomahawk cruise missiles hit infrastructure targets at Isfahan.

“Craters are visible at the Fordo site, Iran’s main location for enriching uranium to 60%,” Grossi said. He added that “entrances to tunnels used for the storage of enriched material appear to have been hit” at Isfahan, as had buildings “related to the uranium conversion process.” At Natanz, he said, the fuel enrichment plant had “been hit again.”

But he said that “no one” including his International Atomic Energy Agency, was “in a position to assess the underground damage at Fordo,” and he called for inspectors to be allowed back “to Iran’s nuclear sites and account for the stockpiles of uranium, including, most importantly, the 400kg enriched to 60%.”

The Trump administration and Israel appear confident they know the location of the highly enriched uranium. Speaking to CBS News’ “Face the Nation” before Grossi made his assessment, Secretary of State Marco Rubio said Sunday that he doubted Iran had been able to move the enriched the uranium and that “we have to assume that there’s a lot of 60% enriched uranium buried deep under the ground there in Isfahan.”