National security communications adviser John Kirby speaks as White House briefing on July 31, 2024. (Photo by Alex Wong/Getty Images)
Washington CNN  — 

The White House on Wednesday said reports of the assassination of a Hamas political leader in Iran “don’t help with the temperature going down,” while repeating calls for a ceasefire deal that would see the release of hostages held by Hamas.

“These reports over the last 24-48 hours certainly don’t help with the temperature going down. I’m not going to be Pollyannaish about it; we’re obviously concerned about escalation,” White House national security communications adviser John Kirby told reporters during the White House press briefing.

While repeatedly declining to comment directly on the strike in Tehran, Kirby eventually acknowledged: “All of this adds to the complicated nature of what we’re trying to get done. And what we’re trying to get done is a ceasefire deal.”

But Haniyeh’s killing removes perhaps the most significant Hamas negotiator from the table at a critical time when US officials have said that a long-sought ceasefire deal is as close as it’s ever been, and as a resolution to the end of the war looms over Biden’s legacy as a one-term president.

The Biden administration has largely avoided commenting on reports around Haniyeh’s death, but Secretary of State Antony Blinken told reporters traveling with him in Singapore the US was “not aware of or involved in” the killing of the Hamas leader.

Former senior State Department official Aaron David Miller expects the administration is “seething” over the killing of Haniyeh.

“Blinken says the US was unaware of the strike on Haniyeh,” Miller told CNN, “but you know the administration must be seething about the timing, location and target of the strike.”

A former senior administration official agreed there is anger inside the administration.

It was “completely unnecessary,” the former official said. “There was no military logic to this operation.”

“Whether we end up in a regional war, the future seems pretty clear,” Miller added. “Seemingly never-ending, grinding wars of attrition between Israel and Iran and its proxies with few, if any, off ramps and prospects for enduring de-escalation.”

Blinken has been working the phones in an effort to keep ceasefire talks on track, speaking with counterparts from two key allies, Qatar and Jordan. In both conversations, according to the State Department, the officials emphasized the need for a ceasefire in Gaza.

“Political assassinations [and] continued targeting of civilians in Gaza while talks continue leads us to ask, how can mediation succeed when one party assassinates the negotiator on the other side?,” Qatar’s prime minister, a principal mediator, wrote on X after news of Haniyeh’s death.

The Qatari post amounted to a direct accusation of Israel, while US officials have shied away from confirming the suspected Israeli operation against Haniyeh.

When Blinken spoke with his Qatari counterpart, he asked Prime Minister Mohammed bin Abdulrahman Al-Thani to convey messages to both Iran and Hezbollah to de-escalate and not retaliate, according to a source familiar with the conversation. The prime minister agreed to relay the message, the source said. A spokesman for the State Department declined to comment.

No parties have declared an end to the ceasefire talks but Haniyeh’s death has significantly chilled the prospects of an imminent agreement.

“It’s too soon to know what impact any of this is going to have on the ceasefire deal,” Kirby said at the briefing.

As recently as earlier this month, Haniyeh was discussing ideas for ending the war with mediators in Qatar and Egypt — conversations that sparked some hope that a framework for a deal was coming into view after months of war, which has killed tens of thousands of Palestinians and plunged Gaza into a humanitarian catastrophe.

His assassination is the most recent escalation that has broadened the scope of the war outside of Gaza and threatens to further draw in Iran and the United States.

It follows a rocket attack that killed 12 children in the Israeli-occupied Golan Heights on Saturday, which Israel blamed on Lebanese militant group Hezbollah, another Iran proxy. Hezbollah has denied responsibility for the attack — the deadliest inside Israel since October 7.

Israel responded with a drone strike in southern Beirut that killed Hezbollah’s most senior military official, Fu’ad Shukr. His killing had been considered the most serious escalation in the war, until the assassination of Haniyeh on Wednesday.

Israeli Prime Minister Benjamin Netanyahu said during a televised statement on Wednesday that Israel has delivered “crushing blows” to its enemies in the last few days.

US officials had held out some optimism about a deal prior to the recent escalations. Late last month, Netanyahu signaled he was ready to make a “partial deal” with Hamas that would lead to the release of only some hostages, while still vowing that he would see the war out until the militant group is eliminated.

While Netanyahu’s statement was at odds with a proposal outlined by President Joe Biden last month — a plan that would include the release of all hostages, Israeli troops withdrawing from Gaza and a permanent ceasefire — hopes that a deal could be reached carried over to Netanyahu’s visit to Washington last week. But during a fiery address to Congress, Netanyahu focused little attention on ongoing negotiations, instead vowing to “fight until we achieve victory” while falsely downplaying Israel’s role in the mounting civilian deaths in Gaza.

The recent events could lead to further strain in Biden and Netanyahu’s decadeslong relationship. The president has said that Israel has already reached goals it had outlined after October 7, called the country’s actions in Gaza “over the top” and suggested that Netanyahu seeks to prolong the war only for the sake of his own political survival.

Iran vowed to retaliate for the assassination on its soil. “You killed our dear guest in our house and now have paved the way for your harsh punishment,” Iran’s Supreme Leader Ayatollah Ali Khamenei said, referring to Israel in a statement. “We consider it our duty to ask for the blood of our dear guest.”

And its foreign ministry blamed the United States “as a supporter and accomplice of the Zionist regime in the continuation of the occupation and genocide of the Palestinians, in committing this heinous act of terrorism.”

Asked about the supreme leader’s response to the killing during Wednesday’s press briefing, Kirby responded: ”We have and will maintain a level of readiness to preserve our national security interest in the region.”

CORRECTION: This story has been updated to correct John Kirby’s title.

CNN’s Abeer Salman, Jennifer Handler and Niamh Kennedy contributed.