The US says it has “credible reports” that Hamas is planning an “imminent” attack on civilians in Gaza, which it says would be a “direct and grave” violation of the ceasefire agreement.
A planned attack against Palestinians would “undermine the significant progress achieved through mediation efforts”, a statement by the state department said.
It did not not provide further details – or how this would be a breach of the US-brokered ceasefire agreed with Israel.
Hamas rejected the US statement as false. It has, however, been re-establishing control – and has had gunfights with a local clan in Gaza – in the power vacuum that followed the Israeli partial withdrawal.
The first phase of the ceasefire deal between is currently in progress – all living hostages have been released and bodies of the deceased are still being returned to Israel.
Also part of the agreement, Israel freed 250 Palestinian prisoners in its jails and 1,718 detainees from Gaza.
Washington said it had already informed other guarantors of the Gaza peace agreement – which include Egypt, Qatar and Turkey – and demanded Hamas uphold its end of the ceasefire terms.
“Should Hamas proceed with this attack, measures will be taken to protect the people of Gaza and preserve the integrity of the ceasefire,” the statement said.
President Donald Trump has previously warned Hamas against the killing of civilians.
“If Hamas continues to kill people in Gaza, which was not the Deal, we will have no choice but to go in and kill them,” Trump said in a post on Truth Social earlier this week.
He later clarified that he would not be sending US troops into Gaza.
Last week, BBC Verify authenticated graphic videos that showed a public execution carried out by Hamas gunmen in Gaza.
The videos showed several men with guns line up eight people, whose arms were tied behind their backs, before killing them in a crowded square.
BBC Verify could not confirm the identity of the masked gunmen, though some appeared to be wearing the green headbands associated with Hamas.
Israel’s military has confirmed that one of two sets of remains handed over to the Red Cross in Gaza on Saturday are those of Ronen Engel. The identity of the second person yet to be announced.
So far, the remains of 11 out of 28 deceased hostages had been returned to Israel.
Israeli Prime Minister Benjamin Netanyahu on Saturday said the Rafah border crossing between Gaza and Egypt would remain closed until Hamas returns the remaining bodies.
The Rafah crossing is a vital gateway for Palestinians who need medical assistance to leave Gaza, and for thousands of others to return.
Separately on Saturday, 11 members of one Palestinian family were killed by an Israeli tank shell, according to the Hamas-run civil defence ministry, in what was the deadliest single incident involving Israeli soldiers in Gaza since the start of the ceasefire.
The Israeli military said soldiers had fired at a “suspicious vehicle” that had crossed the so-called yellow line demarcating the area still occupied by Israeli forces in Gaza.
There are no physical markers of this line, and it is unclear if the bus did cross it. The BBC has asked the IDF for the coordinates of the incident.
The Israeli military launched a campaign in Gaza in response to the 7 October 2023 attack, in which Hamas-led gunmen killed about 1,200 people in southern Israel and took 251 others hostage.
At least 68,000 people have been killed by Israeli attacks in Gaza since then, according to the Hamas-run health ministry, whose figures are seen by the UN as reliable.
In September, a UN commission of inquiry said Israel had committed genocide against Palestinians in Gaza. Israel categorically rejected the report as “distorted and false”.
