WASHINGTON – The message was not getting through. Not through the phone calls or the emissaries or the public statements or the joint committee meetings. And so, frustrated that he was being ignored, President Joe Biden chose a more dramatic way of making himself clear to Israeli leaders. He stopped sending the bombs.

Mr Biden’s decision to pause the delivery of 3,500 bombs to Israel was meant to convey a powerful signal that his patience has limits. While insisting that his support for the Jewish state remains “ironclad”, Mr Biden opted for the first time since the Israel-Hamas war erupted last fall to use his power as Israel’s chief arms supplier to demonstrate his discontent.

The hold on the bombs represents a significant turning point in the 76-year-old relationship between the United States and Israel, historically one of the closest security partnerships in the world. But it may not necessarily be a breaking point. The Biden administration is still allowing other weapons to be sent to Israel and, in fact, officials emphasised that no final decision has been made on the bombs that are currently in limbo. Mr Biden hopes the pause will prompt Israel to change course.

“We’re going to continue to do what’s necessary to ensure that Israel has the means to defend itself,” Defence Secretary Lloyd Austin told senators at a hearing on May 8 as he became the first administration official to publicly confirm the weapons pause. “But that said, we are currently reviewing some near-term security assistance shipments in the context of unfolding events in Rafah.”

Israel’s plans to invade Rafah, the city in the southern Gaza Strip where more than one million Palestinians have taken refuge, have been a source of intense friction with the Biden administration for months. The Israelis maintain they need to go into Rafah to finish destroying Hamas, while the Americans oppose an operation they fear would result in widespread civilian casualties.

The dispute has come to a head in recent days as Israeli Prime Minister Benjamin Netanyahu and his war Cabinet appeared to be approaching a decision to proceed with the military assault on Rafah despite US objections. Administration officials said they had begun reviewing arms in April that could be used in the operation and that Mr Biden had signed off on the bomb hold last week.

“The decision means Biden has decided to use his only real form of leverage over Bibi – withholding weapons,” said Mr Cliff Kupchan, chair of the Eurasia Group, who had just returned from a trip to the Middle East, referring to Mr Netanyahu by his nickname. “It’s a low point for US-Israel relations, as it begins to put Israeli security in play. Biden had no choice. The war is a drag on his election campaign, on Democratic Party unity and on US standing in the world.”

The administration was hoping the pause would send a quiet message and did not announce it publicly at first, but the Israelis leaked it. In the days since, Israel ordered the evacuation of 110,000 civilians in Rafah, conducted air strikes against targets on the edges of the city, sent in tanks and seized the crossing with Egypt. Although these moves were characterised as limited and not the beginning of the promised assault, they touched off alarms in the White House.

The Israeli actions, which came in part in response to Hamas rocket attacks that killed four Israeli soldiers last weekend, seem to be intended to keep the pressure on Hamas to agree to a temporary ceasefire in exchange for the release of some of the hostages taken during the Oct 7 terrorist attack.

Whether such a deal is possible remains uncertain. Central Intelligence Agency director William Burns, who has been deeply involved in the negotiations, met Mr Netanyahu on May 8 in Jerusalem even as other officials conferred in Cairo about competing offers from the two sides.

Reaching such a deal may be the only way to avoid a more serious rupture between Israel and the Biden administration, analysts said.

“What they’re asking for is for Israel not to go into Rafah in a significant way,” said Mr Elliott Abrams, a Middle East specialist at the Council on Foreign Relations who served in multiple Republican administrations. “Barring a hostage deal, I think the Israelis are going to go into Rafah, and it is going to cause a great deal of tension.”

The relationship between the US and Israel has been a singular one since the Jewish state declared its independence in 1948 and then President Harry Truman just 11 minutes later made the US the first nation in the world to recognise it. But the relationship has also long been marked by moments of deep stress.

At first, under both Mr Truman and President Dwight D. Eisenhower, the US refused to sell Israel weapons at all. President John F. Kennedy became the first to open up the arsenal by providing Hawk anti-aircraft missiles. President Lyndon Johnson expanded ties by sending M-48 tanks, A-4 Skyhawk planes and F-4 Phantom planes.

Presidents have held back aid to Israel before to indicate displeasure or influence policy. President Ronald Reagan more than once delayed shipments of warplanes and other munitions out of dissatisfaction with Israeli intervention in Lebanon. President George H.W. Bush postponed US$10 billion in housing loan guarantees to keep American money from being used to finance settlement construction in the West Bank.

Overall, since World War II, the US has given more aid to Israel than any other country in the world. As at 2023, the US had provided US$158.7 billion (S$215.1 billion) to Israel since its founding, the vast bulk of it, or US$124.3 billion, for its military and its missile defences, according to the Congressional Research Service. Under a 10-year memorandum of understanding sealed by then President Barack Obama, Washington currently provides US$3.8 billion a year in military aid, not counting the US$15 billion in additional help approved in April by Congress and signed into law by Mr Biden.

Republicans quickly criticised Mr Biden on May 8 after Mr Austin confirmed reports of the delayed bomb shipment. “This is obscene. It is absurd,” Senator Lindsey Graham of South Carolina told the Defence Secretary at the Senate hearing. “Give Israel what they need to fight the war they can’t afford to lose.”

Mr Mitch McConnell of Kentucky, the party’s leader in the Senate, said he had called Mr Jake Sullivan, the President’s national security adviser, to express his concern to the administration “that the delay of shipment of weapons to Israel is just another way of trying to tell an ally how to conduct the war”. He and House Speaker Mike Johnson later sent a letter to Mr Biden protesting the decision.

On the other hand, Democrats and progressives who have been pressing Mr Biden to limit or cut off arms to curtail Israel’s war said the President’s action was long overdue and still not enough after more than 34,000 have died in Gaza, including both combatants and civilians.

Mr Bernie Sanders, the democratic socialist from Vermont, said Mr Biden’s decision was “absolutely right” but should only be the start. “Our leverage is clear,” he said. “Over the years, the United States has provided tens of billions of dollars in military aid to Israel. We can no longer be complicit in Netanyahu’s horrific war against the Palestinian people.”

The decision got the attention of Mr Netanyahu and his war Cabinet. Mr Shalom Lipner, a long-time adviser to multiple Israeli prime ministers, said it “struck a deep chord of concern within Israel, where people are wondering how limiting Israel’s access to weaponry – a move which is certain to embolden Hamas – might be reconciled with Biden’s oft-repeated ironclad commitment to its security”.

But he added that “it would be to Israel’s strategic detriment for the Netanyahu government to ignore the loud pushback from its main provider of military and diplomatic support”. He predicted that the Prime Minister could try to finesse the dispute by proceeding in a more limited, careful way in Rafah while deflecting blame for any failures of the military operation to Mr Biden.

The 3,500 bombs held back last week include both 2,000-pound and 500-pound munitions. Administration officials said they were particularly concerned that the larger bombs were too powerful to be used with precision in a densely populated urban area like Rafah.

The State Department is also still weighing whether to proceed with the delivery of Joint Direct Attack Munition guidance kits that can convert so-called dumb bombs into precision-guided weapons, but there is no imminent shipment at the moment. Moreover, officials said they would still provide “every dollar” of aid authorised in the new congressional package.

Mr Kupchan said that the course of the US-Israeli relationship would turn on what happens next. If Mr Netanyahu defers to Mr Biden’s judgment on Rafah, it may just be a momentary flare-up. But if the two leaders remain at a stand-off, it could lead to a broader cut-off of weapons, which would have a more lasting effect.

“The foundation of US-Israel relations is so strong that it won’t be significantly damaged by this move,” Mr Kupchan said. “Further withholdings, however, while quite unlikely, would be a different story.” NYTIMES