The killing of Saleh al-Arouri, a top Hamas leader, on Tuesday deprives the group of one of its most skilled tacticians, who helped route money and weapons to its operatives in the Gaza Strip and elsewhere in the Middle East and integrated Hamas more tightly into Iran’s network of forces committed to fighting Israel, according to analysts.

But it was far from clear on Wednesday that his death would be a debilitating blow to the organization, which has rebuilt again and again after assassinations of its leaders, and remained agile enough to plot the Oct. 7 terrorist attacks in southern Israel.

Still, Mr. al-Arouri’s killing — in an explosion in a Beirut suburb that senior officials from Hamas, Lebanon and the United States ascribed to Israel — sets Hamas back at a highly vulnerable time, analysts say. Israel has not taken responsibility for his killing.

Israel’s overwhelming offensive in Gaza has significantly weakened the military strength of Hamas there, including its ability to manufacture rockets and other weapons. Mr. al-Arouri’s position, as Hamas’s de facto ambassador to Iran and Hezbollah, meant that he would have had an important role in the group’s efforts to rebuild militarily with help from foreign backers.

“Hamas will suffer, because it has lost one of its key strategists,” said Emile Hokayem, the director for regional security at the International Institute for Strategic Studies in London. “He was someone who did well managing high-level political relationships and also had credibility as a commander.”

Rebuilding its military capabilities “is going to be the problem for Hamas in the next phase, and it will likely be more dependent on foreign support as its base in Palestine weakens,” Mr. Hokayem added.

Mr. al-Arouri’s assassination also further internationalizes Israel’s war against Hamas, significantly raising the stakes for countries that host Hamas officials and putting new pressures on the group that could, if sustained, transform it.

In recent years, Hamas has operated as a network with nodes across the Middle East. Since 2007, it has been the de facto government for Gaza’s 2.2 million Palestinians, overseeing services like water and electricity while its armed wing frequently battled with Israel. Its operatives also organized covertly in the Israeli-occupied West Bank, while officials in other countries raised money to fund its operations, maintained relationships with its allies and communicated its views to journalists and foreign diplomats.