Israeli airstrikes pounded southern Lebanon after Hezbollah’s leader vowed retribution for the pager and walkie-talkie attacks. Lebanese officials said it was one of Israel’s heaviest bombardments there in months.

The device explosions appeared to be the culmination of a monthslong operation by Israel to target as many Hezbollah members as possible all at once.

Israel launched a series of strikes on Hezbollah targets Thursday as the war against the Lebanon-based group widened in the wake of two consecutive days of deadly explosions triggered in wireless devices.