TEL AVIV: The targeting of two senior militant leaders in two Middle Eastern capitals within hours of each other — with each strike blamed on Israel — risks rocking the region at a critical moment.

The strikes come as international mediators are working to bring Israel and Hamas to agree to a cease-fire that would wind down the devastating war in Gaza and free hostages.

Intense diplomatic efforts are also underway to ease tensions between Israel and Hezbollah after months of cross-border fighting.

The assassination of Hamas’ top leader Ismail Haniyeh in Tehran and the strike against senior Hezbollah commander Fouad Shukur in Beirut could upend those painstaking attempts to defuse a Middle East powder keg.

Iran has also threatened to respond after the attack on its territory, which could drag the region into all-out war.

Here’s a look at the potential fallout from the strikes:

Gaza cease-fire negotiations could crumble

Haniyeh’s assassination could prompt Hamas to pull out of cease-fire negotiations being mediated by the U.S., Egypt and Qatar, though it has yet to comment on the issue.

But given Haniyeh’s role, a senior Egyptian official with direct knowledge of the negotiations said the killing will highly likely have an impact, calling it “a reckless act.”

“Haniyeh was the main link with (Hamas) leaders inside Gaza, and with other Palestinian factions,” said the official, who met with the Hamas leader multiple times in the talks.

“He was the one we were meeting face-to-face and talking about the cease-fire.”

Qatari Prime Minister Mohammed Bin Abdul Rahman al-Thani condemned the attacks.

“How can mediation succeed when one party assassinates the negotiator on the other side?” he wrote on the social media platform X.

U.S. Secretary of State Antony Blinken said he didn’t want to speculate on the effect, but the events renewed the “imperative of getting the cease-fire,” which he said they are working toward on a daily basis.

Hezbollah has said that it will halt its fire on Israel if a Gaza cease-fire is reached.

Israeli Prime Minister Benjamin Netanyahu has argued that military pressure will prompt Hamas to agree to a deal, but previous killings of senior figures have not appeared to increase the chances for an agreement.

People in Gaza expressed sadness and shock over Haniyeh’s killing and worried that a cease-fire deal was slipping away.

“By assassinating Haniyeh, they are destroying everything,” said Nour Abu Salam, a displaced Palestinian.

“They don’t want peace. They don’t want a deal.”

The increasingly desperate families of hostages held in Gaza urged for their loved ones to be released.

“I’m not interested in this assassination or that assassination, I’m interested in the return of my son and the rest of the hostages, safe and sound, home,” said Dani Miran, whose son Omri, 46, was kidnapped from Kibbutz Nahal Oz on Oct. 7.

A broader war on more fronts risks erupting

The strikes also raised alarm among some diplomats working to defuse tensions in the region.

“The events in Tehran and Beirut push the entire Middle East to a devastating regional war,” said one Western diplomat.

The diplomat — whose government has engaged in concerted diplomacy to prevent an all-out war between Israel and Hezbollah, but is not directly involved in cease-fire or hostage negotiations — called the killing of Haniyeh a “serious development” that has “almost killed” a possible cease-fire in Gaza, given its timing and location.

She said that Haniyeh’s killing inside Tehran while attending the inauguration of an Iranian president “will force Tehran to respond.”

The assassination in Tehran is not the first time that Israel has been blamed for a targeted attack on Iranian soil, but it’s one of the most brazen, said Menachem Merhavy, an expert on Iran from the Hebrew University of Jerusalem.

Israel hasn’t taken responsibility for the strike, though it vowed to kill all of Hamas’ leaders over the Oct. 7 attacks.

Merhavy thinks it’s unlikely that Iran will respond directly to Israel, such as with the barrage of 300 rockets in April after a suspected Israeli strike in Syria that killed two Iranian generals in an Iranian consular building.

He believes Iran is more likely to send its response via Hezbollah.

“Iran knows that its capability of hurting Israel is much more significant from Lebanon,” said Merhavy.

The location of Haniyeh’s assassination was just as important as the strike itself, he said.

“The message was to Iran and the proxies, if you thought in Tehran you’re protected, we can reach you there as well,” said Merhavy.

“Reconsider your relations with Tehran, because they cannot protect you on its own soil.”

Targeted leaders can be easily replaced

Although Haniyeh’s name has more international recognition, the strike on Hezbollah commander Fouad Shukur, if successful, is “much more important from a functional point of view,” said Michael Milshtein, an Israeli analyst of Palestinian affairs at Tel Aviv University and a former military intelligence officer.

He said Shukur was involved in the day-to-day management of Hezbollah’s strikes on Israel, including, according to Israel, the rocket attack on Majdal Shams that killed 12 youths on Saturday.

Israel said its hit in Beirut on Tuesday killed him but Hezbollah has not confirmed that.

“If Hezbollah is considering how to act or to respond, one of the main question marks is how they’re going to manage a war without Shukur,” said Milshtein.

Others said Shukur, if he is in fact killed, will easily be replaced.

“Hezbollah has thick layers of commanders and leaders, and the killing of 1 or 10 or 500 will not change the equation,” said Fawaz Gerges, of the London School of Economics.

Gerges said Haniyeh is a much more symbolic leader and is far removed from the day-to-day operations in Gaza.

“Even though the assassination of Haniyeh is a painful blow for Hamas, it will make no difference in the military confrontation between Israel and Hamas,” and Gerges.

He noted that Israel has a long history of assassinating leaders of Palestinian groups, but those strikes have little impact as the leaders are quickly replaced.