Israel killed Hamas deputy leader Saleh al-Arouri in a drone strike in Lebanon’s capital Beirut on Tuesday, Lebanese and Palestinian security sources said, raising the potential risk of the war in Gaza spreading well beyond the Palestinian enclave.

Arouri, 57, was the first senior Hamas political leader to be assassinated since Israel launched a shattering air and ground offensive against the group almost three months ago after its shock assault and rampage into Israeli towns.

Lebanon’s heavily armed Hezbollah group, a Hamas ally, has been exchanging near-daily fire with Israel across Lebanon's southern border since the war in Gaza began in October.

Hezbollah leader Hassan Nasrallah has warned Israel against carrying out any assassinations on Lebanese soil, vowing a “severe reaction.”

Hezbollah said on Tuesday it had targeted a group of Israeli soldiers in the vicinity of Marj with missiles, following Arouri's killing.

Israel has long accused Arouri of lethal attacks on its citizens, but a Hamas official said he was also “at the heart of negotiations” conducted by Qatar and Egypt over the outcome of the Gaza war and the release of Hamas-held Israeli hostages.

Israel neither confirmed nor denied carrying out the killing, but its military spokesperson Rear Admiral Daniel Hagari said Israeli forces were in a high state of readiness and prepared for any scenario.

“The most important thing to say tonight is that we are focused and remain focused on fighting Hamas,” he said when asked by a reporter about the reports of Arouri's killing.

Israel had accused Arouri, a co-founder of the Hamas’ military wing, the Izz-el-Deen al-Qassam Brigades, of ordering and supervising Hamas attacks in the Israeli-occupied West Bank for years.

“I am waiting for martyrdom (death) and I think I have lived too long,” Arouri said in August 2023, alluding to Israeli threats to eliminate Hamas leaders whether in Gaza or abroad.

Nasser Kanaani, spokesperson for the foreign ministry of Iran, a major supporter of Hamas and Hezbollah, said Arouri’s killing would “undoubtedly ignite another surge in the veins of resistance and the motivation to fight against the Zionist occupiers, not only in Palestine but also in the region and among all freedom-seekers worldwide.”

Hundreds of Palestinians took to the streets of Ramallah and other towns in the West Bank to condemn Arouri’s killing, chanting, “Revenge, revenge, Qassam!”

Iranian-backed Houthis rebels in Yeman have vowed to continue their attacks on shipping in the Rea Sea until Israel halts the conflict in Gaza, and warned that it would attack U.S. warships if the militia group itself was targeted.

Houthi militants fired two anti-ship ballistic missiles into the southern Red Sea, though no damage was reported, the U.S. Central Command (CENTCOM) said late on Tuesday.

Britain’s United Kingdom Maritime Trade Operations Authority reported up to three explosions near a merchant vessel in the Bab al-Mandab Strait, east of Eritrea’s Assab, with no reports of damage.

The U.S. has announced an international maritime task force to protect shipping through the Red Sea, which leads to the Suez Canal, a shipping route which carries roughly one third of global container cargo.

The Gaza war was triggered by a shock cross-border Hamas assault on Israeli towns on Oct. 7 in which Israel says 1,200 people were killed and some 240 hostages spirited back to Gaza.

The Gaza health ministry said 207 people had been killed in the past 24 hours, bringing the total recorded Palestinian death toll to 22,185 in nearly three months of war in Gaza.

Israel says it tries to avoid harm to civilians and blames Hamas for embedding fighters among them, an accusation Hamas denies.

The Israeli targeting of Gaza City’s Al Shifa hospital last November stoked global alarm over the fate of civilians and patients who were inside.

Israel said Hamas used tunnels beneath the hospital as a headquarters and was using its patients as shields.

A U.S. official said on Tuesday, citing declassified U.S. intelligence, that U.S. spy agencies assessed that Hamas and Islamic Jihad had used Al Shifa to command forces and hold some hostages but largely evacuated it before Israeli troops entered.

Israeli bombardments have engulfed Gaza’s 2.3 million residents in a humanitarian disaster in which thousands have been left destitute and threatened by famine due to a lack of food supplies.

Shortly before Arouri’s killing, Hamas’ paramount leader Ismail Haniyeh, who is also based outside Gaza, said the movement had delivered its response to an Egyptian-Qatari ceasefire proposal.

He reiterated that Hamas’ conditions entailed “a complete cessation” of Israel's offensive in exchange for further releases of hostages.

Israel believes 129 hostages remain in Gaza after some were released during a brief truce in late November and others were killed during air strikes and rescue or escape attempts.

Israel has vowed to keep fighting until it has wiped out Hamas but it is unclear what it plans to do with the enclave should it succeed, and where that leaves the prospect of an independent Palestinian state.

In Washington, the State Department denounced “inflammatory and irresponsible” statements by Israeli cabinet ministers Bezalel Smotrich and Itamar Ben-Gvir advocating for the resettlement of Palestinians outside of Gaza.

Such statements underscore fears among some in the Arab world that Israel wants to drive Palestinians out of the land where they envision a future state, repeating the mass dispossession of Palestinians when Israel was created in 1948.