President Trump issued an ultimatum to Hamas, saying that if all Israeli hostages are not released from Gaza by noon Saturday, then "all hell is going to break loose."
Asked by reporters for details on what that meant, Mr. Trump initially responded, "You'll find out, and they'll find out too. Hamas will find out what I mean." He then said ending the ceasefire would be "Israel's decision," but that he felt it would be "appropriate" to cancel the agreement if the hostages aren't released by his deadline.
Mr. Trump made the comments about the hostage negotiations while he was signing executive orders at the White House on Monday.
Hamas on Monday said the next hostage release, which was scheduled for Saturday, has been delayed after a spokesman accused Israel of violating the ceasefire agreement by targeting Palestinians in Gaza with airstrikes.
"This includes delays in allowing displaced Palestinians to return to northern Gaza, targeting them with airstrikes and gunfire across various areas of the Strip, and failing to facilitate the entry of humanitarian aid as agreed," said Abu Obeida, the spokesperson for Hamas' armed wing, the Al-Qassam Brigades.
Defense Minister Israel Katz said Hamas' plan to delay the next release of hostages was "a complete violation" of the ceasefire agreement and that he instructed the Israeli military to be on the highest level of alert. The prime minister's coordinator for hostages said the Israeli government intends to live up to its end of the agreement.
The current six-week ceasefire agreement between Israel and Hamas calls for the release of dozens of hostages captured during the Oct. 7, 2023, terrorist attack in exchange for roughly 2,000 Palestinian prisoners.
But as Mr. Trump on Monday threatened to upend that agreement, he said Saturday's delayed hostage release — which was to include the release of three hostages held by Hamas in exchange for the release of hundreds of Palestinian prisoners — should include all remaining hostages.
"I'd say they ought to be returned by 12 o'clock on Saturday," Mr. Trump said, "... all of them, not in drips and drabs, not two and one and three and four and two."
The sides have carried out five swaps since the ceasefire went into effect last month, freeing 18 hostages, including Keith Siegel, who has dual U.S.-Israeli nationality, and over 730 Palestinian prisoners.
The most recent exchange, which took place on Feb. 8, caused some alarm because of the emaciated condition of the three male hostages who were released by Hamas. The Hostages and Missing Families Forum said the three male hostages "endured hell itself," after seeing the state of the men.
Negotiations on the second phase of the ceasefire — which was brokered by the U.S., Qatar and Egypt — have begun, but Mr. Trump may have complicated the situation last week by suggesting the U.S. could "take over" Gaza.
The plan put forth by the president, which he's not backed down from, has drawn tentative backing from Israeli Prime Minister Benjamin Netanyahu's administration, but it has been roundly condemned by many nations in the region and around the world, including the neighbors of Israel to which Mr. Trump said Gaza's population should be relocated.
Three hostages held in Gaza are due to be freed on Saturday in exchange for more Palestinian prisoners held in Israel.
Israel's Defence Minister Israel Katz called the Hamas announcement a "complete violation of the ceasefire agreement".
Key Israeli ally US President Donald Trump has suggested the ceasefire should be cancelled if "all" the hostages held in Gaza are not returned by Saturday.
"I'd say they ought to be returned by 12 o'clock on Saturday... all of them, not in dribs and drabs, not two and one and three and four and two," he said.
"I'm speaking for myself," he stressed. "Israel can override it."
Seventy-three hostages taken during Hamas's attack on Israel on 7 October 2023, and three others taken a decade earlier, are still being held in Gaza.
If hostages were not released, Trump added, "All hell is going to break out."
Asked whether he meant retaliation from Israel, he said: "You'll find out, and they'll find out too. Hamas will find out what I mean."
Katz said he had ordered the Israel Defense Forces to "prepare at the highest level of alert for any possible scenario in Gaza and to protect the communities".
"We will not allow a return to the reality of 7 October," the Israeli defence minister added.
Hamas's announcement came shortly before people gathered in Tel Aviv to mark the 24th birthday of Israeli hostage Alon Ohel, his second in captivity.
He was taken hostage from the Nova festival on 7 October 2023.
Mia Goldstein, an attendee at the rally for Ohel, told the BBC there should be "immense pressure" to get the rest of hostages out, adding Hamas's delay was "horrifying".
Michal Neeman, who took part in a protest in Tel Aviv following the announcement from Hamas, said the hostages "should have been out a few months ago. You see the situation, they are dying there, and their blood is on this government's hands".
UN spokesperson Farhan Haq said "any delays" to the fragile ceasefire deal would be an issue and all parties involved should adhere to their previously stated agreements and timelines.
Hamas has said the "door remains open" to the exchange going ahead on Saturday if Israel "complies" with its obligations, according to news agency AFP.
Hamas spokesman Abu Obeida accused Israel of delaying the return of displaced Palestinians to the north of Gaza, firing on people and failing to allow in agreed humanitarian aid.
The group's announcement did not refer to Trump or US policy but it comes after strong remarks made last week by the US president about the US taking ownership of Gaza and redeveloping it.
His proposal included the resettlement of Palestinians outside the territory and was praised as "revolutionary and creative" by Israeli Prime Minister Benjamin Netanyahu.
The militant group's statement is the latest in a series of recriminatory actions between the two sides.
Israel delayed by two days allowing displaced Palestinians to return to the north of Gaza, accusing Hamas of reneging on a commitment to free a female Israeli civilian hostage.
Israel also recently briefly delayed buses taking Palestinian prisoners to be released into the occupied West Bank, after expressing anger over the way in which hostages were released through crowds of spectators in Gaza hours earlier.
On Friday, Hamas exceeded by a short time a deadline to release the names of hostages to be freed on Saturday - as required under the ceasefire - prompting concern in Israel. This came after it accused Israel of failing to abide by its commitment to boost the amount of humanitarian aid allowed into Gaza –contradicting what had been described by the UN's humanitarian chief as a "massive surge".
Since the ceasefire began on 19 January, 16 Israeli and five Thai hostages have been released in exchange for 566 prisoners.
By the end of the first stage of the ceasefire in three weeks' time, 33 hostages and 1,900 prisoners are expected to have been freed. Israel says eight of the 33 are dead.
Hamas took 251 hostages and killed about 1,200 people when it attacked in October 2023. Israel launched a military campaign in response, killing at least 48,000 Palestinians, according to the Hamas-run health ministry.
