(CNN) — Israel carried out an attack targeting Hamas leadership in Qatar on Tuesday, in an unprecedented strike on a key mediator in the Gaza conflict that threatened to derail renewed peace efforts and further inflame tensions in the region.

A senior Israeli official told CNN that among those targeted was Hamas’ chief negotiator Khalil Al-Hayya. “We are awaiting the results of the strike,” the official said.

Hamas said later Tuesday that the strike killed five members but failed to assassinate the negotiating delegation. Al-Hayya was not listed among the dead, but his son and the director of his office were killed in the strike, Hamas said.

Qatar and Hamas both said that a Qatari security official died in the strike, as well.

Qatar’s prime minister was visibly angry as he described the attack as “state terrorism” at a press conference. “This is a message to the entire region: that there is rogue player in the region,” Sheikh Mohammed bin Abdulrahman bin Jassim Al-Thani said.

The Qatari foreign ministry’s spokesperson, Majed Al Ansari, said “the cowardly Israeli attack” targeted residential buildings housing several members of the Hamas political bureau in Doha.

“While strongly condemning this attack, the State of Qatar emphasizes that it will not tolerate this reckless and irresponsible Israeli behavior,” Al Ansari said on X.

Hours after the strike, Israeli Prime Minister Benjamin Netanyahu announced that Israel accepted a new US ceasefire proposal and that the attack could bring the end of the war closer.

“The days when the heads of terror enjoyed immunity anywhere are over,” Netanyahu said in Hebrew at a US embassy event in Jerusalem. “I will not allow such immunity for the murderers of our people.” An Israeli security official said the operation “could potentially generate a shift” that could bring an end to the war in Gaza, though it’s unclear how targeting the chief Hamas negotiator would lead to such a change.

Qatar has been a key mediator in Gaza ceasefire talks, maintaining direct channels with the US, Israel and Hamas. It has also hosted multiple rounds of negotiations, and senior Israeli officials – including the head of the Mossad spy agency and top Israeli negotiators – have visited Doha. Whether such visits will continue remains uncertain.

Einav Zangauker, the mother of an Israeli hostage held in Gaza, said Tuesday’s strike could serve as a death sentence for her son.

“I am trembling with fear. It could be that at this very moment, the prime minister has essentially executed my Matan, sentenced him to death,” Zangauker wrote on X. “Why is he insisting on blowing up every chance for a deal?”

Antonio Guterres, the Secretary-General of the United Nations, condemned the attack, saying “Qatar has been playing a very positive role to achieve a ceasefire and release of all hostages,” according to a UN spokesperson.

The Israeli strike involved more than 10 fighter jets which fired more than 10 munitions, according to an Israeli official, and they all struck a single target in the Qatari capital.

‘Israel takes full responsibility’

An Israeli source who spoke to CNN said the United States was informed ahead of the strike. Two US officials confirmed to CNN that the Trump administration had been notified.

In a statement, the Israeli Prime Minister’s Office said, “Today’s action against the top terrorist chieftains of Hamas was a wholly independent Israeli operation. Israel initiated it, Israel conducted it, and Israel takes full responsibility.”

The short missive appeared designed to distance the US from the Israeli attack on a critical American ally in the Middle East.

White House press secretary Karoline Leavitt called the strike “unfortunate” and said it ran counter to US President Donald Trump’s goals in the region. “Unilaterally bombing inside Qatar, a sovereign nation and close ally of the United States that is working very hard in bravely taking risks with us to broker peace, does not advance Israel or America’s goals,” she said.

Still, Leavitt’s carefully worded statement made clear that “eliminating Hamas” was a “worthy goal,” and stopped short of condemning Israel’s actions.

Later on Tuesday, Trump sought to further distance himself from the attack, posting an addendum to an earlier statement from the White House that specified the decision was made by Israel’s leader and that the US learned of it too late to intervene.

“This was a decision made by Prime Minister Netanyahu, it was not a decision made by me,” Trump wrote on Truth Social, inserting the line into a statement read earlier from the White House briefing room by Leavitt.

Trump added that by the time his administration learned of the attack and told the Qataris, there was little he could do to stop it. Qatar’s prime minister said earlier that the US contacted Qatar 10 minutes after the attack occurred, and that Israel used weapons that went undetected by radar.

‘Trusted strategic ally’ of the US

Qatar’s Amiri Diwan said in a statement that Trump expressed his solidarity with Qatar following the attack, in a phone call with Qatar’s Emir, Sheikh Tamim bin Hamad Al-Thani.

Trump “stressed that the State of Qatar is a trusted strategic ally of the United States of America, calling on His Highness the Amir to continue Qatar’s mediation efforts to end the war in the Gaza Strip,” the statement said.

Two Israeli sources said the attack, which the IDF called “Summit of Fire,” had been planned about two or three months ago but was accelerated in recent weeks.

Qatar has denied receiving prior notification of the strike, calling reports that suggested otherwise “baseless.”

Qatar is one of the US’ closest allies in the Middle East and home to the Al Udeid Air Base, the biggest American military facility in the region. A key security partner of Washington, it was designated a Major Non-NATO Ally in 2022.

Al Udeid came under Iranian attack this year after the US struck nuclear facilities in Iran during Israel’s June campaign.

Following Tuesday’s strike, the US embassy in Qatar instituted a shelter-in-place order for its facilities in the country, it said in a post on X.

“We have seen reports of missile strikes occurring in Doha. The US Embassy has instituted a shelter-in-place order for their facilities. US citizens are advised to shelter-in-place,” it said. The order was later lifted but the embassy said it will continue to monitor the situation.

Shortly after the explosion in Qatar, the IDF issued a statement saying it had targeted “senior leadership” of Hamas with “a precise strike” in a joint operation with the Shin Bet security agency.

“For years, these members of the Hamas leadership have led the terrorist organization’s operations, are directly responsible for the brutal October 7th massacre, and have been orchestrating and managing the war against the State of Israel,” the IDF said.

On Monday, Khalil Al-Hayya met with Qatari Prime Minister Sheikh Mohammed bin Abdulrahman Al-Thani in Doha.

During the discussion, Al-Thani pressured Hamas to “respond positively” to a US ceasefire proposal for Gaza, according to an official familiar with the meeting. The proposal, which was put forward this week, called on Hamas to release all Israeli hostages in exchange for negotiations to end the war in the enclave.

It’s not the first time Israel has carried out an attack that undermines US diplomatic efforts. In June, Israel opened a military campaign against Iran while Washington was in talks with Tehran over its nuclear program. Although both the US and Iran had already voiced doubts about making progress, the Israeli strikes effectively ended any chance of an agreement.