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US Secretary of State Antony Blinken and Defence Secretary Lloyd Austin have told Israel that weapons shipments could be affected unless it addresses the “deteriorating humanitarian situation” in Gaza within 30 days.
The secretaries wrote to Israeli officials on Sunday to tell them that military assistance could be at risk due to the legal implications of giving such aid when international humanitarian law is being breached.
“We are writing now to underscore the US government's deep concern over the deteriorating humanitarian situation in Gaza, and seek urgent and sustained actions by your government this month to reverse this trajectory,” they wrote in a letter, first reported by Axios and Israel's N12 news channel.
US officials confirmed that Mr Austin and Mr Blinken had cosigned a letter to their Israeli counterparts.
“Secretary Blinken sent a similar letter in April, which received a constructive response and concrete measures from the Israelis. This letter follows a recent decrease in assistance reaching Gaza, which we aim to similarly address with concrete measures," a US defence official said.
Mr Blinken and Mr Austin cited Section 620i of the Foreign Assistance Act National Security Memorandum 20, which requires that parties receiving military assistance conduct themselves within international humanitarian law.
“To reverse the downward humanitarian trajectory and consistent with its assurances to us, Israel must, starting now and within 30 days, act on the following concrete measures,” they wrote before listing bullet points of improvements the US would need to see in Gaza.
Mr Blinken and Mr Austin said Israel would need to “surge all forms of humanitarian assistance” and “ensure that the commercial and Jordan Armed Forces corridors are functioning at full and continuous capacity”.
They also said Israel must “end isolation of northern Gaza”.
Israel has cut off the northern strip from the rest of Gaza with a siege blocking food, water, medication and aid since October 1, and ordering forced mass displacement of the people remaining there.
Three hospitals in the north are struggling to continue operations, the World Health Organisation reported. Palestinians have shared experiences of coming under violence when trying to flee, and health officials have reported dozens killed.
State Department spokesman Matthew Miller reported that humanitarian aid entering Gaza has “fallen by over 50 per cent from where it was at its peak” and said the US would like to see changes before 30 days.
“This particular letter that we're talking about now follows a decrease in humanitarian assistance to the people of Gaza, which is obviously something we've been very, very concerned about since the beginning of the conflict,” White House National Security spokesman John Kirby said.
More than 43,300 people have been killed in the enclave during Israel's military operations, the Gaza Health Ministry said, after a Hamas-led attack on southern Israel on October 7 last year. More than 2 million people have been internally displaced.
The letter was addressed to Minister of Defence Yoav Gallant and Minister of Strategic Affairs Ron Dermer. The Israeli Ministry of Defence declined to immediately comment on it.
The threat by President Joe Biden's administration is a rare move against its ally Israel, which it has stood by throughout its war amid a rising civilian death toll and risks of a wider Middle East conflict. It is estimated that the US has sent a record $17.9 billion of military aid to Israel, despite much global and domestic criticism.
Mr Kirby said that the letter was “not meant as a threat”, but was to “reiterate the sense of urgency we feel” about the necessity of humanitarian assistance.
The US has paused one shipment of 2,000-pound bombs over concerns of weapons used in densely populated civilian areas in May.
Mr Biden's administration in May issued a review that said it was “reasonable” Israel was violating international law, but deemed that “provision of defence articles” could continue as normal. Critics at the time condemned the report as “untruthful”.
Former House speaker Nancy Pelosi told CNN on Monday evening that “the leverage we have given [Israel Prime Minister Benjamin] Netanyahu has been used in a way that is most destructive”.
Jewish-American Congresswoman Sara Jacobs, who is on the House foreign affairs committee, on Monday responded to images of Palestinians burning alive after an Israeli strike in Gaza by saying Mr Netanyahu “clearly doesn't care about [US] concerns”.
“The only time he's ever changed behaviour is when we've exerted our leverage. It's time to do that now,” Ms Jacobs said.
Amir Avivi, a retired Israeli brigadier general, told The National that a halt in US weapons supplies would lead Israel to produce more of its own defence supplies.
“The long-term effect of this is that in Israel there is a growing understanding that we have to rely more on ourselves, and produce our own weapons … and this is happening. Israel is building factories at the moment,” Mr Avivi said.
On Tuesday, Israel tested new anti-drone technology at a field in the country's south, according to the ministry.
Mr Avivi said Israel would see Washington as an “unreliable ally” if it halted weapons supplies: “I don't think it would be a smart move by the US and it's sending a bad message to their allies.”
The US last week told the UN Security Council that Israel must address “catastrophic conditions” that Palestinian civilians are experiencing in the besieged Gaza Strip, in another rare moment of American pressure on Israel to stop “intensifying suffering”.
Thomas Watkins, Jihan Abdalla, Ellie Sennett in Washington, and Lizzie Porter in Jerusalem contributed reporting
