Withholding US weapons from Israel could force changes in how it fights but may not stop its devastating assault

• The US paused a shipment of bombs to Israel last week amid rising concerns over a Rafah assault.
• On Wednesday, President Joe Biden warned that Washington may block additional weaponry.
• It's a politically significant move that could have military implications as well.

After seven months of war in the Gaza Strip, US military support for Israel has arrived at a pivotal moment in recent days: it no longer appears to be unconditional.

Last week, the US paused a shipment of bombs to Israel — marking the first time since the war began last fall that Washington has done so — amid rising concerns that the country was gearing up for a major military operation in the southern Gaza city of Rafah.

Then, on Wednesday, President Joe Biden warned he would withhold additional weaponry, including artillery, if Israel pressed forward with a widespread ground assault on the city, where more than 1 million Palestinian civilians have sought refuge.

The Biden administration's decision is a politically significant move that appears designed to apply pressure on Israeli Prime Minister Benjamin Netanyahu's government to do more to protect civilians in Gaza. Experts say that there could also be military implications as Israel continues to wage war.

Biden is controlling 'one variable'

The weapons shipment that the US put on hold last week was supposed to include 1,800 2,000-pound bombs and 1,700 500-pound bombs, according to multiple US officials. A final determination on what to do with this shipment has yet to be made.

Israel has relied heavily on its inventory of the larger, 2,000-pound bombs throughout the war to go after Hamas' vast underground tunnel network. These air-dropped munitions can be outfitted with precision-guidance kits, but even then, they are still capable of causing lots of collateral damage. The State Department is also mulling whether to deliver more of these kits, known as Joint Direct Attack Munitions.

For now, these holds are primarily symbolic, Daniel Byman, a senior fellow with the Transnational Threats Project at the Center for Strategic and International Studies think tank, told Business Insider. But that could change over time.

The depth of Israel's stockpile is unclear, but it is believed to have a sufficient supply of munitions to continue fighting in Gaza without this particular shipment of US weaponry, said Byman, a former Middle East analyst for the US intelligence community. But "the campaign may take a while, and as we know, munitions can be used up very, very rapidly in these circumstances," he added.

Hamas isn't Israel's only enemy though, and it wants to have a sizable stockpile of munitions to be ready for the possibility of a full-scale conflict with Lebanon's Hezbollah — another Iranian proxy group like Hamas. That would be a more difficult fight for the Israeli military, Byman said. Whether the US would actually withhold weaponry in that case is unknown.

During a Wednesday interview with CNN's Erin Burnett, Biden acknowledged that civilians in Gaza have been killed by US-provided 2,000-pound bombs. He then said that he would withhold additional weaponry beyond the one shipment last week if the Israeli military proceeds with a major ground invasion in Rafah.

"If they go into Rafah, I'm not supplying the weapons that have been used historically to deal with Rafah, to deal with the cities, to deal with that problem," Biden said. "We're not going to supply the weapons and the artillery shells have been used."

Earlier this week, Israel ordered civilians to evacuate eastern Rafah before announcing a "precise counter-terrorism operation" in the area, during which Israeli military seized control of the Palestinian side of a key crossing with Egypt that it said was being used for "terrorist purposes."

The IDF said as part of its new activity, ground troops and fighter jets were striking Hamas targets in the Rafah area. The White House later described the operation as "limited," and Biden on Wednesday said Israel's actions so far haven't crossed his red line.

Raphael Cohen, the director of the Strategy and Doctrine Program at the RAND Corporation think tank's Project AIR FORCE, explained to BI that by withholding 2,000-pound and 500-pound bombs, the US could force Israel to conduct more ground maneuver in Rafah, rather than an intense air campaign like what was seen earlier in the conflict.

It's unclear if that would "necessarily save — minimize — Palestinian civilian casualties, but it does change the nature of combat," said Cohen, a former lieutenant colonel in the US Army Reserve. Putting a hold on artillery could also force Israel to carry out more high-precision raids, instead of clearing the entire city, he added. There is uncertainty there as well though.

"The problem is that the Biden administration is controlling one variable, which is munitions," Cohen said.

"It's all well and good to try to go after Hamas via commando raids," he added, but he cautioned that "the targets have to lend themselves to that kind of operation. It's not clear, to me at least, that that's necessarily the operational reality on the ground."

The military utility of Biden's move ultimately has to be weighed against how important Israel views Rafah toward achieving its security objectives, Cohen said. "Countries are willing to go to great lengths if they feel their vital national interest is threatened, and fight even in suboptimal ways."

Israel vows to 'stand alone'

The decision to withhold weapons and Biden's latest warning that he would potentially put a pause on other support follows repeated efforts by the US to press Israel to present a credible plan that would limit civilian casualties ahead of any large-scale Rafah operation.

It is not necessarily an unprecedented move, as past US administrations have also threatened to withhold military support from Israel. But this decision does represent a notable shift in Biden's approach to the war. Since Hamas' Oct. 7 terror attacks, the US has been unwavering in sending Israel a massive amount of weaponry, despite growing international concerns about the rising death toll in Gaza.

John Kirby, the spokesperson for the White House National Security Council, told reporters on Thursday that despite the single shipment of bombs being held up, the Biden administration is still sending weapons to Israel, which is getting the "vast, vast majority of everything that they need to defend themselves."

For now, it remains to be seen how Israel proceeds with its military action in Rafah, but officials have been defiant in saying that they will continue to hunt down Hamas, regardless of how much international support the country retains.

"If we need to stand alone, we will stand alone," Netanyahu asserted on Thursday, per a translation. "I have said that if necessary, we will fight with our fingernails."