In a Region on Edge, Israel and Hezbollah Launch Major Attacks on Each Other

Amid fears of an all-out war between Israel and Hezbollah forces in Lebanon, the two sides on Sunday mounted the biggest round of cross-border strikes since the war in Gaza began, with Israel bombing dozens of sites in a pre-emptive attack, and Hezbollah launching hundreds of rockets and drones.

Within hours, both sides appeared to de-escalate, at least temporarily, but signaled that the violence and dangerous tensions could continue. Hezbollah said its operation, vengeance for the Israeli assassination of a senior commander, had “finished for the day,” but left open the possibility of further action. Prime Minister Benjamin Netanyahu of Israel said that “what happened today is not the final word.”

For weeks, Israelis have waited in trepidation for a major attack promised by Hezbollah in retaliation for the airstrike last month in a suburb of Beirut that killed one of its leaders, Fuad Shukr. Iran, which backs both Hezbollah and Hamas, has also vowed retribution for the killing of Ismail Haniyeh, the Hamas political leader, on a visit to Tehran, hours after Mr. Shukr was killed, though it appears to have put that plan on hold.

After the Hamas-led attacks on Oct. 7 that triggered the war in the Gaza Strip, Hezbollah began firing frequently on Israel, prompting widespread Israeli bombardment. Repeated strikes, counter-strikes and threats have forced more than 160,000 people to evacuate on both sides of the border, stoking fears that the conflict would ignite full-scale regional war pitting Israel not only against Hezbollah — a more potent force than Hamas — but also its patron Iran.

Before dawn on Sunday, Israel’s military said it used about 100 warplanes to strike more than 40 Hezbollah launch sites in Lebanon, saying it had acted to prevent a major attack. Lebanon’s Health Ministry said at least three people had been killed and two others hurt, and Israel said a soldier was killed and two others wounded during the Hezbollah barrage.