TEL AVIV — Israel and the United States are preparing for a potential Iranian attack on Israel, as efforts to secure a ceasefire in Gaza intensify ahead of the expected resumption of formal negotiations this week.

Mediators have urged Israel and Hamas to return to the negotiating table in a renewed push to strike a ceasefire deal after the talks risked being derailed by the recent assassinations of Hezbollah and Hamas leaders which Iran and its Lebanese proxy have vowed to avenge.

Negotiations are set to resume in the Egyptian capital Cairo or the Qatari capital Doha on Thursday. Last week, the United States, Egypt and Qatar – key mediators in talks between Israel and Hamas – said they will use the meeting to present a “final bridging proposal” and urged both sides to attend.

A major Iranian attack reprisal against Israel could risk disrupting the ceasefire talks that US officials have said were at an advanced stage prior to the assassination of Hamas’ political leader Ismail Haniyeh in Tehran, which Iran blamed on Israel. Israel hasn’t confirmed or denied responsibility.

In a joint statement Sunday evening, France, Germany and the United Kingdom endorsed the calls for the warring parties to strike a deal, saying “there can be no further delay” given the simmering threat of a regional conflagration.

The White House said Monday that it shares Israel’s concerns and expectations about an attack from Iran in the coming days, pointing to increased American force posture in the region as preparation for an Iranian reprisal.

“It’s difficult to ascertain, at this particular time, if there is an attack by Iran and its proxies what that would look like,” National Security Council spokesman John Kirby said.

But State Department deputy spokesperson Vedant Patel said in a separate press briefing Monday: “We fully expect these talks to continue to move forward.” Patel would not say outright who the US believes is the biggest obstacle to achieving a deal, but said that the onus is on Hamas to agree to a ceasefire.

Israel said it will send a delegation to the Thursday talks, but Hamas hasn’t confirmed its attendance, even if it has signaled that it still wants a deal.

Following Haniyeh’s assassination, Iran’s Supreme Leader Ayatollah Ali Khamenei said Haniyeh’s death would “not pass in vain,” and its Islamic Revolutionary Guard Corps warned that “blood vengeance” for the killing is “certain.”

Iranian President Masoud Pezeshkian furthered those threats on Monday, telling a Vatican official in a phone call that the assassination warrants Iran’s right to “self defense” and to “respond to an aggressor,” Iranian state news agency IRNA reported.

There have been some indications that Iran may abandon plans to attack Israel if a ceasefire deal is reached. But the country’s mission to the United Nations said on Saturday that Tehran’s retaliation to Israel’s suspected killing of Haniyeh is “totally unrelated to the Gaza ceasefire,” adding that it has a right to self-defense.

The US and Israel continued preparations for that scenario over the weekend. US Defense Secretary Lloyd Austin ordered a guided missile submarine, the USS Georgia, to the Middle East and accelerated the arrival of a carrier strike group to the region, the Pentagon said Sunday evening. The US also released $3.5 billion to Israel to spend on US weapons and military equipment, months after it was appropriated by Congress. And on Monday, the Israeli military suspended vacation flights for permanent personnel in anticipation of an attack.

Iran’s UN mission said it hopes that its attack on Israel “will be timed and conducted in a manner not to the detriment of the potential ceasefire.”

“Direct and intermediary official channels to exchange messages have always existed between Iran and the United States, the details of which both parties prefer to remain untold,” it added.

Meanwhile, Hezbollah – the Iran-backed militant group in southern Lebanon – fired a barrage of about 30 rockets toward northern Israel Sunday night. Although rocket fire toward Israel from Lebanon has become a near-daily occurrence since the outbreak of war in Gaza, Israeli officials fear a larger-scale response from Hezbollah after the assassination of the group’s top military commander Fu’ad Shukr in a Beirut suburb last month

But as the world watched Iranian airspace and the Israel-Lebanon border, the worst of the weekend’s fighting was again confined to the Gaza Strip, as an Israeli strike on a mosque and school in Gaza City killed at least 93 Palestinians on Saturday, according to local officials.

With the number of Palestinians killed during 10 months of war edging closer to 40,000, Israel’s strike sparked global condemnation. Qatar and Egypt condemned the strike, calling it a violation of international law, and the US National Security Council said the White House was “deeply concerned” about reports of civilian casualties.” In the aftermath, the three mediators renewed their calls for the warring parties to agree to a ceasefire deal.

Although the Israel Defense Forces (IDF) said it had targeted a Hamas command post and killed several fighters, the strike was a reminder that, despite its earlier claims to have dismantled Hamas in the north of the Strip, the militant group has reassembled in areas previously deemed clear.

After Haniyeh’s assassination, Hamas named Yahya Sinwar – its leader in Gaza and one of the masterminds of the October 7 attack on Israel – as the new head of its political bureau, suggesting that Hamas’ most extreme faction had taken over, further dimming hopes of a ceasefire deal.

But, following the call from mediators last week to return to talks, Hamas requested a plan to implement the existing offer proposed by US President Joe Biden in July, rather than pursuing additional negotiations.

“Out of concern and responsibility towards our people and their interests, the movement demands the mediators to present a plan to implement what they presented to the movement and agreed upon on July 2, 2024, based on Biden’s vision and the UN Security Council resolution, and to compel the occupation (Israel) to do so, instead of going for further negotiation rounds or new proposals,” Hamas said in a statement Sunday.

A regional source familiar with the talks told CNN on Monday that Hamas is planning to attend the diplomatic talks. The organization’s mixed messaging comes as each side involved in the negotiations positions itself to try to take advantage and pressure opponents in the run-up to the high-stakes talks.

Egyptian and Qatari mediators have told Israel that Sinwar wants a deal, an Israeli source familiar with the matter told CNN. The source said that US officials have made clear to their Israeli counterparts that the time to strike a deal is now, in order to prevent a regional war.

But, despite growing pressure at home to help bring the hostages home, Israeli Prime Minister Benjamin Netanyahu has repeatedly stymied attempts to reach an agreement.

“Nobody knows what Bibi wants,” one Israeli source said, calling Netanyahu by his nickname.

Netanyahu accused his defense minister Yoav Gallant of adopting an “anti-Israel narrative” following reports in Israeli media about a closed meeting Gallant had with parliament.

Gallant allegedly told lawmakers that last October he had proposed to preemptively attack Hezbollah in Lebanon, that Netanyahu had not supported the strike, and that current conditions for such a strike have now changed. He also allegedly called Netanyahu’s “absolute victory” line, a slogan regularly used by the prime minister, “nonsense”.

The comments irked Netanyahu, prompting him to issue the statement criticizing the Israeli defense minister. “He should have attacked Sinwar, who refuses to send a delegation to the negotiations, and who was and remains the only obstacle to the hostage deal,” Netanyahu said in a written statement.

Gallant responded to the critcism on X, saying: “I’m determined to meet the goals of the war and to continue the fighting until Hamas is dismantled and the hostages return.”

Though not directly addressing his leaked comments, Gallant said leaks from “sensitive and confidential forums” was one of the “weak points that were discovered during the war” and that “we must act against it with all severity.”

“We are facing challenging days in which we’ll be required to stand firm and take powerful defensive and offensive actions,” Gallant said. — CNN