DUBAI — Iranian President Ebrahim Raisi, a hard-line protégé of the country’s supreme leader who helped oversee the mass executions of thousands in 1988 and later led the country as it enriched uranium near weapons-grade levels and launched a major drone-and-missile attack on Israel, has died. He was 63.

Mr. Raisi’s sudden death, along with Iran’s foreign minister and other officials in a helicopter crash Sunday in northwestern Iran, came as Iran struggles with internal dissent and its relations with the wider world. A cleric first, Mr. Raisi once kissed the Quran, the Islamic holy book, before the United Nations and spoke more like a preacher than a statesman when addressing the world.