The head of the UN’s nuclear watchdog says US strikes on Iran fell short of causing total damage to its nuclear program and that Tehran could restart enriching uranium “in a matter of months,” contradicting President Donald Trump’s claims the US set Tehran’s ambitions back by decades.

Rafael Grossi, the head of the U.N.’s nuclear watchdog, disputed President Donald Trump’s assessment that Iran’s missile sites were “totally obliterated” by U.S. airstrikes earlier this month.

Rafael Mariano Grossi, director general of the International Atomic Energy Agency, told CBS that Iran had a "a very vast ambitious" nuclear program.

Iran said that more than 900 people were killed in its nearly two-week war with Israel, which subsided with a ceasefire shortly after the U.S. carried out strikes on three of Iran’s underground nuclear facilities.

The current ceasefire between Israel and Iran is fragile and likely temporary, with both sides expressing deep mutual distrust. Israeli Defense Minister Israel Katz has warned that “immunity is over” for Iran,