Israel’s military said in a statement early on Monday it launched multiple air and artillery strikes overnight on what it said were Hezbollah military targets in Lebanon.

The strikes came after the militant group said on Sunday it had launched its “largest” air operation, sending explosive drones at a mountaintop Israeli military intelligence base in the annexed Golan Heights.

It is the latest incident among escalating cross-border exchanges of fire that have triggered global alarm.

Announcing “the largest operation” carried out by its aerial forces, Hezbollah said in a statement that its fighters sent “multiple, successive squadrons of drones to target the reconnaissance center” on Mount Hermon.

The Israeli military said an explosive drone “fell in an open area in the Mount Hermon area” but there were “no injuries.”

Hezbollah said the drone attack was part of its “response” to the killing of an operative in a strike Saturday deep into east Lebanon around 100 kilometers (60 miles) from the border.

The Mount Hermon attack targeted intelligence systems, “destroying them and starting a major fire,” Hezbollah said.

In two additional statements, the military said its air defenses “successfully intercepted” several “aerial targets” that crossed from Lebanon after sirens sounded in the Golan Heights area.

Israel seized the Golan Heights from Syria in 1967 and later annexed it in a move largely unrecognized by the international community.

The Israeli strike on Saturday killed “a key operative in Hezbollah’s Aerial Defense Unit,” the military has said.

Throughout Sunday, Hezbollah announced four more attacks on Israeli military sites across the border with barrages of rockets as well as some guided missiles. Israeli authorities reported four wounded.