The killing of Hamas leader Saleh al-Arouri in a reported drone strike in Beirut will be perceived as a warning to Iran, which has armed and financed Hamas, and other Hamas leaders, experts said.

Al-Arouri, the commander of Hamas’ military wing in the West Bank and deputy chairman of the group’s political bureau, was a key figure who had helped repair Hamas’ relations with Iran and had been in Israel’s crosshairs even before the current conflict began. He was killed Tuesday with six other members of the organization after his home in a suburb in southern Beirut was targeted by a drone strike.

“There’s no single cog in this group without whom the whole thing falls apart, but Arouri was a particularly important person, both in terms of overall leadership and his support for violence,” said Matthew Levitt of the Washington Institute for Near East Policy think tank.