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, a think tank.

Levitt was the deputy assistant secretary for intelligence and analysis at the Treasury Department from 2005 to 2007 and a counterterrorism adviser at the State Department.

Lebanese officials, Hamas and the Lebanese-based militant group Hezbollah all laid blame for the strike on Israel. Israeli officials declined to comment.

Israel will be braced for retaliation from Hezbollah, which is backed by the Iranian regime, but it most likely concluded removing al-Arouri was worth the risk, Levitt said.

“They didn’t just kill some random Hamas leader, someone who just speaks in front of a camera. They actually took out someone who was operationally important,” he said.

Hezbollah leader Sayyed Hassan Nasrallah has vowed to retaliate against any Israeli targeting of Palestinian officials in Lebanon.

Mark Regev, an adviser to Israeli Prime Minister Benjamin Netanyahu, told NBC News that Israel has not taken responsibility for the strike.

Regev did not deny nor confirm whether Israel authorized the strike but said it was a “surgical” hit on Hamas, rather than an attack on Lebanon.

The CIA declined to comment.