Israel launched a wave of airstrikes against Hezbollah targets in southern Lebanon, just as the militant group’s leader said two days of exploding pagers and walkie-talkies amounted to a declaration of war.

U.N. peacekeepers in Lebanon urged immediate de-escalation as hostilities rumbled on at the Lebanese-Israeli border on Friday, following Israel's most intense airstrikes in nearly a year of conflict with the Iran-backed Hezbollah.