Hezbollah did not immediately confirm the death of Ibrahim Aqeel. The United States had accused him of being involved in bombings that killed more than 200 U.S. Marines and many others in Beirut in 1983.

The attack represents another security failure for the militant group that has been reeling from repeated Israeli blows.

The strike on Hezbollah’s stronghold in Lebanon's capital is a major escalation adding to fears of an all-out war.