A day after a blast killed a senior Hamas leader outside Beirut, Lebanon, many Israelis welcomed the assassination as an important step in the campaign to destroy the militant group, but worried it might carry costs.

Members of Prime Minister Benjamin Netanyahu’s right-wing coalition in Israel, in particular, cheered the attack. “All those involved in the October massacre should know we’ll get to them, and we’ll settle the score,” declared Danny Danon, a member of Parliament from the Likud party.

But some analysts said the killing of the Hamas official, Saleh al-Arouri, was likely to disrupt any negotiations over freeing more hostages taken in the Hamas-led attack on Oct. 7 — which would be another setback for Israeli families waiting desperately for their relatives to come home.

The assassination also prompted fears of a wider war in the Middle East and of retaliatory attacks in Israel.

On Wednesday, the leader of the Lebanese-based militant group Hezbollah, which like Hamas is backed by Iran, denounced the killing as a “dangerous” escalation and warned that Israel would “not go unpunished.”

“If the enemy considers waging a war against Lebanon, our battle will be without boundaries or rules,” Hassan Nasrallah, Hezbollah’s leader, said in a broadcast. “We are not afraid of war.”