Israel-Hamas War: Killing of Senior Leader Carries Risks for Israel, Analysts Say

While the death of Mr. al-Arouri, a key strategist and liaison with Hamas’s Iranian sponsors, was a blow to the group, analysts said, it has rebounded before. And the assassination adds fuel to tensions along Israel’s northern border with Lebanon, home of Hezbollah, another Iran-backed group that has waged war with Israel. Hezbollah’s frequent rocket fire has forced evacuation border communities, and the group has warned that any assassination in Lebanon would draw a strong response.

Even so, members of Prime Minister Benjamin Netanyahu’s extreme right-wing government welcomed the killing and the show of strength it displayed. “So shall your enemies perish, Israel,” Bezalel Smotrich, the far-right finance minister, wrote on social media, quoting from the Old Testament.

Danny Danon, a member of Parliament from Mr. Netanyahu’s Likud party, posted, “All those involved in the October massacre should know we’ll get to them, and we’ll settle the score.”

Israel has not taken responsibility for the strike that killed Mr. al-Arouri and several comrades, but officials with Hamas, Lebanon and the United States have said Israel was behind it, which Israelis appeared to take for granted.

On Wednesday, a State Department spokesman, Matthew Miller, said at a daily news briefing that the United States had not been forewarned of the strike. “We continue to believe it is not in Hezbollah’s interest, just as it is not in Israel’s interest, to escalate this conflict in any way,” he said.

Given the multiple risks and unclear benefits, Ehud Olmert, a former prime minister, questioned why the decision was made to kill Mr. al-Arouri now. Mr. al-Arouri’s focus had always been the West Bank, not Gaza, he said.

“Was he that important? I’m not so sure,” Mr. Olmert said. “There is room to ask this question. Was it urgent? Was it important to do this now? And was it more important than other things?”

Many families of hostages are increasingly skeptical of Mr. Netanyahu’s promises to make the return of the captives a top priority in the war, and fear that they could be murdered or mistreated in retaliation to the assassination.

“Of course this doesn’t help — it hurts,” said Lior Peri, whose 79-year-old father, Chaim, was kidnapped from Kibbutz Nir Oz. “I don’t know who’s in charge and giving the order, but they’re definitely not thinking about the hostages.”

“A gamble” is how a column in the Israeli newspaper Yediot Ahronoth labeled the killing on Wednesday.

“Of all the possible reactions Hamas may take, the most disconcerting is with regard to the hostages,” wrote the columnist, Nachum Barnea. “The argument that the assassination will soften Sinwar’s position is just a story we tell ourselves,” he wrote, referring to the Hamas leader, Yahya Sinwar, adding that the killing was likely to “delay, or even torpedo, the negotiations” for their release.

Mr. Netanyahu met with representatives of hostage families on Tuesday evening, around the very time that the strike took place, and told them efforts to free their loved ones were continuing. “The contacts are being held; they have not been cut off,” he said.

Israel, familiar with the seemingly endless cycle of attacks and counterattacks in the Middle East, is bracing for retribution.

Many residents who live along the northern border with Lebanon have already been displaced from their homes for months because of rocket fire by Hezbollah, with whom Mr. al-Arouri had worked closely.

After the killing, Rear Adm. Daniel Hagari, the Israeli military’s chief spokesman, said in a televised briefing that Israeli forces were “on very high alert on all fronts, for defensive and offensive actions.” He emphasized that Israel was “focused on fighting Hamas,” in what some Israeli analysts interpreted as a suggestion that it did not seek a wider war with Hezbollah.

Israeli public support for destroying Hamas is broad but not unqualified: After almost three months of war in Gaza, and amid growing international pressure to limit the rising number of Palestinian civilian deaths, many Israelis are beginning to voice out loud questions about whether the goal is realistic, and whether the country could bear the toll it would take to achieve it.

Most senior Hamas leaders within Gaza have eluded capture, and though Israel has begun pulling some troops out of the enclave in what appears to be the start of a shift toward a new stage of the war, few in the country were prepared for a conflict of this length and with such heavy casualties.

Michael Crowley contributed reporting.