Ali Larijani, a senior Iranian security official and influential conservative figure, was killed in an Israeli airstrike, Iranian authorities confirmed. He was 67. His death comes weeks after strikes by the United States and Israel killed Iran’s supreme leader, triggering an escalating conflict that has driven much of the country’s leadership underground.

Though ineligible to become supreme leader because he was not a Shiite cleric, Larijani was widely believed to be effectively running the country in the aftermath of the leadership vacuum. He had recently been appointed to advise on nuclear negotiations and had traveled to Oman for talks shortly before the war began. Iranian officials said his son, Morteza Larijani, was also killed in the strike.

Born into a prominent political family, Larijani held several powerful posts over decades, including culture minister, parliament speaker, and head of the Supreme National Security Council. Known for his increasingly hard-line positions, he was under heavy United States sanctions and had been implicated in the repression of mass protests. He also authored several books on philosophy, including works examining Immanuel Kant.