Iran’s supreme leader on Tuesday pledged to avenge the deaths of three commanders and four officers in Iran’s armed forces, one day after they were killed in a precision Israeli airstrike on the Iranian embassy compound in Damascus.

The leaders, Iranian officials said, were some of the highest ranking leaders in the Quds Force, overseeing Iran’s covert intelligence and military operations in Syria and Lebanon. The strike was the deadliest against Iranian officials in recent memory and has shaken the country’s armed forces establishment.

The strike, both the latest in a yearslong shadow war between Iran and Israel and a seeming escalation in that conflict, has again brought attention to Israel and Iran’s conflicting ambitions in the region and the network of proxies Iran employs to fight its battles.

“We will make them regret this crime and similar crimes, with the help of God,” Ayatollah Ali Khamenei, the supreme leader, said of the Israelis.

Here’s what we know about the commanders who were killed.

How important were the slain Quds Force commanders?

Among the officers killed on Monday was Gen. Mohammad Reza Zahedi, a veteran of the Revolutionary Guards Corps and its external branch the Quds Forces. General Zahedi, three Iranian officials and a Guard member said, was the corps’ top commander in the region, in charge of Iran’s network of proxy militias, particularly those in Lebanon and Syria.