One week ago, US President Donald Trump was given a hero's welcome in Israel after securing the Gaza ceasefire and exchange of Israeli hostages for Palestinian prisoners.

But the days since have shown just how precarious the ceasefire is, and Sunday brought its biggest test so far.

The Israel Defense Forces (IDF) launched a series of deadly strikes across Gaza, after two soldiers were killed in the southern city of Rafah in an attack it blamed on Hamas. Hamas said it was not responsible because it had not had contact with fighters in the area since communications were cut off in March.

An Israeli security official announced the suspension of aid deliveries as a result of the attack.

It appears US pressure ensured the truce was not derailed and that Israel's crossings with Gaza reopened on Monday. Now it is clear mediators must stay closely involved to shore up the deal and settle key issues on the future of Gaza and Hamas.

Already, the president's special envoys Steve Witkoff and Jared Kushner are back in the region while Hamas negotiators are meeting Egyptian mediators and Palestinian factions in Cairo.

All are expected to discuss the second phase of Trump's 20-point peace plan, which involves deploying an international stabilisation force in Gaza, the eventual withdrawal of the IDF and critically, the disarmament of Hamas.

Palestinians and Israelis have been shaken by the latest breakdown.

"From the start of the war I was with him 24 hours a day, I never left him," bereaved father, Shadi Abu Obeid told the BBC in Khan Younis as he fought back tears at the funeral of his 14-year-old son Mohammed early on Monday.

"Because of the ceasefire I was a bit more relaxed, and I let him go out with his friends," Shadi added. "It was quiet and there were meant to be international guarantees."

Mohammed was killed with two others in an Israeli strike on a tent in al-Mawasi. The IDF would not comment on who or what was specifically being targeted.

At least 45 Palestinians were killed, local hospitals say, after the IDF said it struck "dozens of Hamas terror targets throughout the Gaza Strip".

The BBC understands that several members of Hamas's armed wing, including a commander, were killed in a strike on a makeshift café in central Gaza. However, footage from other locations showed civilians, including children, among the dead.

Trump's envoys – who played a key role in negotiations with Hamas – had been expected in Israel to meet Prime Minister Benjamin Netanyahu, prior to the latest events.

Before they left the US, the two men gave an interview to 60 Minutes on CBS, in which they described how they had broken with diplomatic protocols to hold direct talks with Hamas leaders during ceasefire talks in Sharm el-Sheikh in Egypt.

They said this was intended to give guarantees that fighting would not resume after Israeli hostages were returned. Kushner - Trump's son-in-law – said the president had been "very, very comfortable" with such an approach.

He also said the signs were that Hamas was acting "in good faith" to return the bodies of deceased hostages – a main point of contention with Israel, prior to Sunday's events, threatening the ceasefire. Sixteen bodies have yet to be handed back. Hamas has said it has recovered another corpse which will be handed back when "conditions allow."

Speaking to journalists on Air Force One on Sunday, President Trump stressed the truce remained in place and that "we want to make sure it's going to be very peaceful".

When it came to the threat of internal violence and score-settling by Hamas in Gaza, he said that Hamas had been "quite rambunctious" and "they've been doing some shooting". But he added that "maybe the leadership isn't involved", and that it could be "some rebels within".

The IDF denied reports that its actions on Sunday were triggered by a clash between Hamas and a militia allied to Israel in the city of Rafah, in southern Gaza. It said Hamas had launched several direct attacks on its troops in an area still under its control with an anti-tank missile and gunfire.

An Israeli government spokeswoman said forces had been working near Rafah "to dismantle terrorist infrastructure all in accordance with the ceasefire agreement."

Hamas, which has accused Israel of multiple ceasefire violations, said communication with its remaining cells in Rafah had been cut off for months and that it was "not responsible for any incidents occurring in those areas".

The latest events have Israeli commentators focusing once again on the weaknesses of the deal agreed by Israel and Hamas.

In Israel's Haaretz newspaper, journalist and author Amir Tibon notes that it was "full of vague wording that left significant loopholes."

One problem that he says it left unresolved "was the fate of Hamas fighters stranded in the areas of Gaza held by Israel when the ceasefire went into effect". Israel's military currently holds about half of the territory, demarcated by a so-called Yellow Line.

In Israel Hayom, military columnist Yoav Limor describes the firefight near Rafah as "a warning", adding: "If Israel fails to establish tough and clear rules vis-à-vis Hamas it could find itself on a slippery slope."

Israel's Defence Minister, Israel Katz, has since appeared to do that, putting out a message that any Hamas fighters beyond the Yellow Line, in Israeli-controlled parts of Gaza must leave immediately and that Hamas leaders will be held responsible for their actions.

With Palestinians expressing confusion about the exact location of the line, the IDF has put out a video showing bulldozers towing yellow blocks into place to mark it out.

On Monday, Palestinian health officials said Israeli fire killed three people east of Gaza City. The IDF said its troops fired towards "several terrorists" who crossed the Yellow Line in the Shejaiya area.

Tough rhetoric and domestic pressure on Netanyahu are now anticipated as Israel's parliament begins its winter session, and with an internal election due within the prime minister's Likud party.

Netanyahu directed the military to take "strong action" against breaches of the deal, but he refrained from threatening a return to war.

On the Palestinian side, Hamas spokesman Mohammed Nazzal has called for the speedy approval of a committee of politically independent Palestinian technocrats to govern Gaza, telling Al Jazeera that Hamas had submitted a list of more than 40 proposed names to mediators.

However, in a separate interview with Reuters, he indicated that Hamas intended to maintain security control in Gaza for an interim period, illustrating another major obstacle to cementing the full end of the war in Gaza.

In the US, Vice President JD Vance has downplayed the shakiness of the ceasefire, saying: "There's going to be fits and starts." It was, he said, "the best chance for a sustainable peace".

Meanwhile, Witkoff and Kushner are expected to go on to further meetings in Cairo. There are significant obstacles to overcome before there can be more celebrations over the Gaza ceasefire.