The war in Gaza has devastated much of the territory / AFP

The Trump administration has redoubled its efforts to bolster a fragile ceasefire in Gaza after a flare-up of violence, with Vice President JD Vance due in Israel on Tuesday hot on the heels of two high-level envoys.

Despite incidents over the weekend, both warring parties have said they are committed to the US-backed truce, and Donald Trump himself said Monday that he would give Hamas a chance to "behave" or else be "eradicated".

The ultimatum came as militants returned the body of another dead hostage under the ceasefire deal, with the Israeli military confirming the remains were back in Israel where they would be positively identified. 

Prior to the latest handover, Hamas had given back 12 hostages' bodies out of the 28 it had pledged to return, but it says it needs time and technical assistance to recover them all.

The truce, which Trump helped to broker, came under threat over the weekend when two Israeli soldiers were killed in Gaza's south.

In response, Israel carried out dozens of strikes targeting Hamas across the territory on Sunday -- using 153 tonnes of bombs, according to Netanyahu -- and accused the militant group of "a blatant violation" of the ceasefire, an accusation it denied.

"We made a deal with Hamas that they're going to be very good, they're going to behave, they're going to be nice," Trump told reporters at the White House, adding that "if they're not, we're going to go and we're going to eradicate them".

Trump clarified that American forces would not be involved, but "Israel would go in in two minutes, if I asked them".

"But right now, we haven't said that. We're going to give it a little chance," he added.

Trump had previously said that as far as he was concerned, the ceasefire was still in effect.

His special envoy Steve Witkoff and adviser son-in-law Jared Kushner met with Netanyahu on Monday to discuss recent developments, Shosh Bedrosian, spokeswoman for the prime minister's office, told journalists.

And Netanyahu later told parliament that Vice President Vance would arrive in Israel on Tuesday for discussions on "two things... the security challenges we face and the diplomatic opportunities before us".

- UN calls for calm -

The ceasefire, which began on October 10, halted more than two years of war between Israel and Hamas.

The deal established the outline for hostage and prisoner exchanges, and proposed an ambitious roadmap for Gaza's future. But its implementation has quickly faced challenges. 

Following the flare-up over the weekend, the United Nations said it was "concerned by all acts of violence in Gaza".

"We urge all parties to honour all of their commitments to ensure the protection of civilians and avoid any actions that could lead to a renewal of hostilities and undermine humanitarian operations," said the secretary-general's spokesman, Stephane Dujarric.

Gaza's civil defence agency said Israeli strikes killed at least 45 people across the territory on Sunday.

The agency, which operates under Hamas authority, said four people were also killed by Israeli gunfire on Monday in Gaza City, with the army saying it fired at militants who crossed a ceasefire line.

Under Trump's 20-point plan, Israeli forces have withdrawn beyond the so-called "Yellow Line" -- which leaves them in control of around half of Gaza, including the territory's borders, but not its main cities.

Israeli troops have fired on Gazans they say were approaching their new positions several times since the ceasefire was declared. 

Media restrictions in Gaza and difficulties in accessing many areas mean AFP is unable to independently verify details provided by the civil defence agency or the Israeli military.

- 'Renewed enforcement' -

The army said that after carrying out Sunday's air strikes in response to the attack on its soldiers, it had "renewed enforcement of the ceasefire" but would "respond firmly to any violation".

Hamas denied knowledge of any attack, with one official accusing Israel of fabricating "pretexts" to resume the war.

A Hamas delegation was in Cairo on Monday for talks with Qatari and Egyptian mediators on the continuation of the truce and an upcoming intra-Palestinian dialogue hosted by Egypt, according to a source close to the negotiations.

The war, triggered by Hamas's October 7, 2023 attack on Israel, has killed at least 68,216 people in Gaza, according to the health ministry in the Hamas-run territory, figures the United Nations considers credible.

The data does not distinguish between civilians and combatants but indicates that more than half of the dead are women and children.

Hamas's 2023 attack resulted in the deaths of 1,221 people, mostly civilians, according to an AFP tally based on official Israeli figures.

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