The location where Arouri was killed Tuesday — in Dahieh, a densely populated residential neighborhood on the edge of Beirut where Hezbollah holds sway — was seen as especially provocative, compounding concerns that the Lebanese militant group, which has traded fire with Israel along their shared border but avoided all-out war, might feel compelled to ratchet up its response.

While Israel has not publicly claimed Tuesday’s attack, it has vowed to hunt down Hamas leaders and exact revenge on those complicit in Oct. 7. The Israeli military’s punishing war in Gaza has killed more than 22,000 Palestinians, according to the Gaza Health Ministry, but the group’s leadership structure remains largely intact.

Last month, Israeli media published leaked recordings from Ronen Bar, the head of Israel’s internal security agency Shin Bet, pledging to locate and take out Hamas leaders “in every location” in the world, including Lebanon, Turkey and Qatar.

“It will take a few years, but we will be there in order to do it,” he said in recordings aired by the Kan public broadcaster. “This is our Munich,” he added, referring to a series of Israeli assassinations in the 1970s that targeted Palestinians involved in killing 11 Israelis at the 1972 Munich Olympics.

Nasrallah’s speech, announced in December, was meant to commemorate the anniversary of the U.S. assassination of top Iranian commander Qasem Soleimani in Iraq in 2020. But analysts anticipate he will pivot to Tuesday’s attack, which Hamas said killed six other members of the group, including two commanders in the Izzedine al-Qassam Brigades, the military arm of Hamas that Arouri helped to found.

Arouri regularly met with Nasrallah, who has been in hiding since Lebanon’s 2006 war with Israel. A Hezbollah spokesperson confirmed the two men were scheduled to meet Wednesday, because “every time he’s here, he meets with the Sayyed,” referring to Nasrallah.

Arouri “was the one who traveled between here and Turkey; he had the link between inside [Gaza] and Hezbollah,” the spokesperson told The Washington Post, speaking on the condition of anonymity because of the group’s rules. “He was a big player, both politically and militarily.”

Arouri was seen as a political envoy of sorts, said Amal Saad, a lecturer of politics and international relations at Cardiff University who closely follows Hezbollah. In 2017, Arouri was part of a Hamas delegation that visited Iran, at a time when relations between the two parties had deteriorated over differing positions on Syria’s civil war.

Arouri’s assassination came as Israel announced the withdrawal of some of its troops from northern Gaza, part of what it has described as the “third phase” of the war. Nasrallah’s speech is expected to offer clues about how Hezbollah will act during this new phase, Saad said.

“He’s not really going to give any details; the party never does, he never does,” Saad said. But because of Israel’s vow to target Hamas leaders for years to come, Nasrallah should expect more attacks on Lebanese soil, she said.

What protected Hamas leaders in Lebanon, she said, was “the balance of deterrence,” she said, “knowing Israel wouldn’t dare” attack Beirut. Now that the threshold has been crossed, she said, measures will have to be put in place to protect the remaining leadership outside Gaza, which would probably entail going underground or into hiding. This could be what saves Lebanon from an all-out war, she added.

There were two messages from Tuesday’s attack, Saad said. “One is to Hezbollah: You can’t harbor Hamas operatives anymore. Lebanon is not going to be a sanctuary for Hamas and Islamic Jihad.” The second, more obvious message, she said, is to Hamas leaders: that nowhere is safe.

Hezbollah’s challenge, she added, will be to respond in a careful and calculated manner “to ensure that Israel understands that you can’t do this again,” but without dragging the country into a full-scale war.

In August, Arouri told the Lebanese Al-Mayadeen channel that the repeated Israeli threats against his life are “part of the price we pay.” The 57-year-old said he had not expected to make it to his current age, and predicted that assassinations and other actions by the Israeli government could push the region into “a comprehensive war.”

Since October, Iranian-allied groups around the region, including Hezbollah, have retaliated for Israel’s Gaza offensive, with attacks targeting Israeli or U.S. interests.

The threat of a broader regional conflagration, though, has remained ever-present as the attacks have continued and even escalated, drawing more forceful rhetoric and military responses from the United States and Israel.

Some of the most disruptive attacks have been staged by the Houthis, a militant group that controls northern Yemen and also has ties to Iran. The group has carried out missile and drone attacks on commercial vessels in the Red Sea, saying it aims to prevent Israeli-owned ships, or vessels bound for Israel, from transiting as long as the siege of Gaza continues.

On Sunday, an attempt by Houthi militants to board a container vessel in the Red Sea culminated in a firefight between U.S. Navy helicopters and the militants, killing 10 Houthi gunmen. It was the first direct engagement since October between the U.S. military and the militant group, and led to fears of further escalation in one of the world’s busiest maritime routes.

Before Tuesday’s killing of Arouri, Israel had stepped up its attacks beyond its borders, including with suspected strikes inside Syria. One such strike, on Damascus on Christmas Day, killed a high-ranking Iranian general, Seyed Razi Mousavi, according to Iranian state media.