Hamas has announced the next release of Israeli hostages is delayed until further notice, accusing Israel of repeatedly violating the Gaza ceasefire deal over the past three weeks.
In response, US President Donald Trump said if all Israeli hostages held in Gaza were not returned by noon on Saturday he would propose cancelling the ceasefire and letting "all hell break out".
"I'm speaking for myself," Mr Trump said. "Israel can override it."
Saturday marks the expected release of the next group of Israeli hostages under the ceasefire.
In a statement, Hamas said Israel had delayed the return of Palestinians to northern Gaza, continued shelling and shooting at Palestinians across the strip, and failed to allow enough aid to enter the territory.
Hamas said it would delay further hostage releases until Israel complied with the terms of the ceasefire deal and compensated the Palestinians for the breaches.
"The delay in the release of prisoners serves as a warning message to the occupation, and to exert pressure for the full compliance with the agreement's terms," Hamas said in a statement.
The group said it "reaffirms its commitment to the terms of the agreement".
Israeli military prepares for resumption of fighting
Israel’s Defence Minister Israel Katz ordered the military to prepare for a potential resumption of fighting.
"Hamas' announcement to stop releasing Israeli hostages is a complete violation of the ceasefire agreement and the deal to release the hostages,” he said in a statement.
"I have instructed the IDF 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 October 7."
Israeli protesters gathered in Hostages Square in Tel Aviv after the announcement.
In the second week of the ceasefire, Israel had delayed the opening of crossings in the Netzarim Corridor – preventing displaced Gazans from crossing between northern and southern areas of the strip.
That was in protest over chaotic scenes during one of the hostage handovers, where crowds surged towards the Israeli captives as they were being presented to the Red Cross.
Israel has also denied limiting aid deliveries into Gaza.
Negotiations surrounding the second phase of the ceasefire, after the current agreement lapses on March 2, have been underway in Qatar.
An Israeli delegation had been sent to Doha for those talks, and returned on Monday local time.
Israeli Prime Minister Benjamin Netanyahu called an urgent meeting with military officials and said he was bringing forward a scheduled meeting of the country’s security cabinet.
Families call on mediators to 'restore' the deal
Hundreds of Israelis blocked roads in the commercial capital, Tel Aviv, in protest at this latest obstacle to the hostage release.
Groups representing the hostage families said they were calling on the mediators of the ceasefire agreement, Egypt and Qatar, to “help restore the deal’s implementation”.
Doubts are growing about the likelihood of reaching the second phase of the ceasefire deal, in which Hamas releases all remaining living hostages and both sides declare a “sustainable calm”.
Egyptian officials have reportedly said that Hamas no longer regards the United States as a guarantor for the deal, given Mr Trump has announced he plans to forcibly relocate nearly 2 million Gazans so the territory can be turned into a real estate development.
In an interview with Fox News, the president said Palestinians would not be allowed to return to Gaza “because they’re going to have much better housing”.
“We'll build beautiful communities for the 1.9 million people. We’ll build beautiful communities, safe communities. Could be five, six, could be two.”
Mr Trump also said he was confident Egypt and Jordan could be convinced to take Palestinians because the US gave them billions of dollars in funding.
