Iran’s supreme leader was killed in U.S.-Israeli airstrikes, a seismic development in a conflict that’s spread to half a dozen countries across the Middle East and threatens to disrupt energy flows.

U.S. President Donald Trump said in a social post that Ayatollah Ali Khamenei, “one of the most evil people in history, is dead.” Iran confirmed the news hours later, saying the government will observe 40 days of national mourning for the 86-year-old ruler, who was killed in his office compound.

“Heavy and pinpoint bombing, however, will continue, uninterrupted throughout the week or, as long as necessary,” Trump said.