Saleh al-Arouri, the deputy Hamas leader who the group said was assassinated in a suburb of Beirut on Tuesday, was accused of masterminding attacks on Israel and had helped usher in a closer relationship between Hamas and Hezbollah, the Iran-backed militia in Lebanon.
The chief of Hamas’s West Bank operations, Mr. al-Arouri was killed in an explosion that also killed two leaders of its armed wing, Hamas said, blaming a “Zionist raid.”
In recent years, Mr. al-Arouri spent much of his time in Beirut, where he served as a sort of Hamas ambassador to Hezbollah, according to regional security officials. He was also regarded as being close to Yahya Sinwar, the Hamas leader in Gaza.
In 2014, Israel accused Mr. al-Arouri, then a Hamas commander, of planning the kidnapping and killing of three Israeli teenagers in the West Bank. Mr. al-Arouri called the act “a heroic operation by the Qassam Brigades,” referring to Hamas’s military wing.
That year, Israel also accused Mr. al-Arouri, who was in exile in Turkey at the time, of plotting to overthrow Mahmoud Abbas, the president of the Palestinian Authority, which governs parts of the Israeli-occupied West Bank.
Mr. al-Arouri was elected in 2017 as deputy chairman of Hamas’s political bureau, accelerating what analysts and Israel officials have contended was a growing relationship between Hamas and Hezbollah. A few days after his election, he visited Tehran to strengthen ties with Iran, and publicly met soon after to discuss collaboration with the head of Hezbollah, Hassan Nasrallah, according to Palestinian news reports from the time.
The U.S. State Department has for years offered up to $5 million for information on Mr. al-Arouri’s whereabouts.
In October, after the Hamas-led attack that killed more than 1,200 people in Israel, Mr. al-Arouri was seen meeting with Mr. Nasrallah and Ziad Nakhale, the secretary general of Palestinian Islamic Jihad, another Gaza-based militant group. The three discussed how to coordinate “in order to achieve an all-out victory and to stop the brutal attack on the oppressed people of Gaza and the West Bank,” according to Al-Manar, Hezbollah’s official broadcaster.
Fighting between Israel and Hezbollah has spread along the Israel-Lebanon border, raising fears of a broader conflict that would draw in Iranian-backed armed groups in Lebanon, Syria, Iraq and Yemen.
Ben Hubbard contributed reporting.