The Biden administration has warned Israel that it must increase the amount of humanitarian aid it is allowing into Gaza within the next 30 days or it could risk losing access to US weapons funding.

US Secretary of State Antony Blinken and Defence Secretary Lloyd Austin warned their Israeli counterparts in a letter dated Sunday that the changes must occur.

The letter, which restates US policy toward humanitarian aid and arms transfers, was sent amid deteriorating conditions in northern Gaza and reports Israel had conducted a strike on a hospital tent site in central Gaza that killed at least four people.

A similar letter that Mr Blinken sent to Israeli officials in April led to more humanitarian assistance getting to the Palestinian territory, State Department spokesman Matthew Miller said on Tuesday. But that has not lasted.

“In fact, it’s fallen by over 50% from where it was at its peak,” Mr Miller said. “So the secretary, along with Secretary Austin, thought it was appropriate to make clear to the government of Israel that there are changes that they need to make again, to see that the level of assistance making it into Gaza comes back up from the very, very low levels that it is at today.”

Israel Palestinians
A Palestinian woman and child after an Israeli strike hit a tent area in the courtyard of Al Aqsa Martyrs hospital in Deir al Balah, Gaza, on Monday (Abdel Kareem Hana/AP)

For Israel to continue qualifying for foreign military financing, the level of aid getting into Gaza must increase to at least 350 trucks a day, Israel must institute additional humanitarian pauses and provide increased security for humanitarian sites, Mr Austin and Mr Blinken said.

They said Israel had 30 days to respond to the different requirements.

“The letter was not meant as a threat,” White House national security spokesman John Kirby told reporters.

“The letter was simply meant to reiterate the sense of urgency we feel and the seriousness with which we feel it, about the need for an increase, a dramatic increase in humanitarian assistance.”

An Israeli official confirmed a letter had been delivered but did not discuss the contents.

The official, speaking on condition of anonymity, confirmed the US had raised “humanitarian concerns” and was putting pressure on Israel to speed up the flow of aid into Gaza.

The letter, which an Axios reporter posted a copy of online, was sent during a period of growing frustration in the administration that despite repeated and increasingly vocal requests to scale back offensive operations, Israel’s bombardment has led to unnecessary civilian deaths and risks plunging the region into a much wider war.

“We are particularly concerned that recent actions by the Israeli government, including halting commercial imports, denying or impeding 90% of humanitarian movements” and other restrictions have kept aid from flowing, Mr Blinken and Mr Austin said.

The Biden administration is increasing its calls for its ally and biggest recipient of US military aid to ease the humanitarian crisis in Gaza while assuring that America’s support for Israel is unwavering just before the US presidential election in three weeks.

Funding for Israel has long carried weight in US politics, and Mr Biden said this month that “no administration has helped Israel more than I have”.

Humanitarian aid groups fear that Israeli leaders may approve a plan to seal off humanitarian aid to northern Gaza in an attempt to starve out Hamas, which could trap hundreds of thousands of Palestinians who are unwilling or unable to leave their homes without food, water, medicine and fuel.

UN humanitarian officials said last week that aid entering Gaza is at its lowest level in months. About 80 trucks carrying aid have entered through crossings in Gaza’s north since October 1, down from roughly 60 trucks a day previously, according to the UN website tracking deliveries.

Cogat, the Israeli body facilitating aid crossings into Gaza, denied that crossings to the north have been closed.

US officials said the letter was sent to remind Israel of both its obligations under international humanitarian law and of the Biden administration’s legal obligation to ensure that the delivery of American humanitarian assistance should not be hindered, diverted or held up by a recipient of US military aid.

Israel’s retaliatory offensive since the October 7 2023 attacks by Hamas has killed nearly 42,000 people in Gaza, according to the territory’s health ministry, which does not distinguish between civilians and combatants in its count.

The Hamas attacks that launched the war killed some 1,200 people, mostly civilians, and militants abducted another 250.

The US has spent a record total of at least 17.9 billion dollars (£13.7 billion) on military aid to Israel since the war in Gaza began and led to escalating conflict around the Middle East, according to a report for Brown University’s Costs of War project.

That aid has enabled Israel to purchase billions of dollars worth of munitions it has used in its operations against Hamas in Gaza and Hezbollah in Lebanon. However many of those strikes also have killed civilians in both areas.

Meanwhile, the UN humanitarian office is warning that the situation is “catastrophic” in northern Gaza, where only three hospitals are operating and Israeli military operations have intensified.

UN spokesman Stephane Dujarric said on Tuesday that the escalation in the north is “severely compromising people’s access to means of survival”. He said the UN’s health partners report that the three hospitals “have dire shortages of fuel, of blood, of trauma items and medications”.

With military action continuing outside, he said, about 285 patients remain in Kamal Adwan Hospital, Al-Adwa Hospital and the Indonesian Hospital.

Mr Dujarric said the UN World Health Organisation warned that Kamal Adwan hospital “remains overwhelmed, receiving between 50 and 70 new injured patients each day”.

With dwindling food stocks, he said the UN Office for the Co-ordination of Humanitarian Affairs known as OCHA said available food supplies are still being delivered, including more than 110,000 meals in Gaza City every day.

However, “there is barely any food left to distribute, and most bakeries will be forced to shut down again in just days without any additional fuel”, the UN spokesman said.

In the first two weeks of October, OCHA reported that just one of its 54 efforts to get to the north was facilitated by Israeli authorities, Mr Dujarric said.

He said 85% of the requests were denied, “with the rest impeded or cancelled due to various logistical or security reasons”.