The leaders of the United States, Qatar and Egypt issued a joint statement Thursday evening calling on Israel and Hamas to return to the negotiating table on Aug. 15 to finalize a cease-fire and hostage release agreement, saying “there is no further time to waste nor excuses from any party for further delay.”

“The three of us and our teams have worked tirelessly over many months to forge a framework agreement that is now on the table with only the details of implementation left to conclude,” said the statement, signed by President Joe Biden, Egyptian President Abdel Fatah El-Sisi and Qatari Emir Tamim bin Hamad Al Thani.

“It is time to release the hostages, begin the ceasefire, and implement this agreement,” the statement said.

Israeli Prime Minister Benjamin Netanyahu’s office said in a statement it would send a delegation to the resumed negotiations, to be held in Cairo or Doha, Qatar, “to finalize the details for implementing the framework agreement.” Hamas gave no immediate response.

The new initiative came as Iran has threatened a massive retaliation in response to the assassination last week of Hamas political leader Ismail Haniyeh in Tehran, which came soon after an Israeli airstrike near Beirut that killed a senior leader of Iranian-backed Hezbollah. Haniyeh was the main Hamas negotiator in the cease-fire talks.

Since then, the United States has reiterated its pledge to defend Israel and substantially reinforced its air and naval assets in the region, including the Middle East deployment early Thursday of Air Force F-22 Raptors.

A senior administration official who briefed reporters on the new cease-fire initiative said it was “not tied to the larger picture” of the Iranian threat. “This is about ‘we need to get this deal done.’”

But “if it influences them,” the official said of Iran, “that’s fine. I would say, if they launch a major war in the Middle East, with some massive attack on Israel — which they’re threatening — that’s obviously going to significantly jeopardize any hope of getting a cease-fire in Gaza.”

The last round of indirect talks mediated by the three governments ended nearly two weeks ago in Rome, when Israel presented new demands to the framework that Biden made public on May 31. Administration officials from Biden on down were reportedly furious at Netanyahu’s last-minute ultimatum, as were senior Israeli military and political leaders.

The three-leader statement expressed the same sense of urgency, in nearly the same words, that the administration has used over the past few months as hopes rose and fell that a cease-fire agreement was near. Both the statement and the official briefing implied that it was an ultimatum.

“As mediators, if necessary, we are prepared to present a final bridging proposal that resolves the remaining implementation issues in a manner that meets the expectations of all parties,” the statement said. The senior official provided no details about how a “final” proposal by the mediators would be enforced.

Describing the genesis of the statement, the senior official, who spoke on the condition of anonymity under rules set by the White House, said that it began with a call Monday between Biden and King Abdullah II of Jordan that included Vice President Kamala Harris and U.S. military leaders regarding the defense of Israel in the event of an attack on Israel “from Iran or Hezbollah or anyone else.”

“And then on Tuesday, the president had … in-depth discussions” with Tamim and Sisi that “really delved into the hostage process. And out of that came the very constructive proposal to issue a joint statement.” Israel was “receptive,” the official said, and “both Qatar and Egypt believe this would be very useful as they’re working on the Hamas side.”

Biden met with his national security team in the Oval Office on Thursday to “review our military deployments, which are ongoing and quite significant and substantial,” the official said.

At the same time, “we’ve been in fairly in-depth discussions with the Israelis … and we do think there’s a way forward here,” the official said. “I would just emphasize it’s incumbent upon not just the Israeli side, but also the Hamas side.”

The official said: “We think the bulk of the work has been done and the deal is really there. And with some force of will, and sitting down to hash it out,” it is possible to reach an agreement.

“Both sides have positions on about four or five issues … and if you just look at them, they might be unbridgeable,” the official added.

But “there needs to be a way forward here. We have lives on the line, particularly the hostages’,” the official said.