Biden and Netanyahu's fraught relationship hits new low after U.S. pauses weapons shipment

"It's definitely an earthquake."

That's how American diplomat Richard Haass described the stunning declaration by U.S. President Joe Biden that his administration would stop supplying certain weapons to Israel if it went ahead with a planned invasion of Rafah in the Gaza Strip.

"This was building up for a while, and Rafah was the straw that broke the camel's back," Haass, former president of the Council on Foreign Relations and policy advisor during the George W. Bush administration, said in an interview with Israeli newspaper Haaretz.

"There's real skepticism in the administration that Rafah will bring about a deal for the hostages, like the Israelis have been saying."

The last several weeks have seen a fraught back and forth between Israel and Hamas and the Qatari, Egyptian and American mediators trying to come up with a deal that will allow a cease-fire between the warring parties and a release of the hostages still held by the Palestinian militant group.

Israeli Prime Minister Benjamin Netanyahu has long pushed for an invasion of Rafah — Gaza's southernmost city where more than a million displaced Palestinians are sheltering — saying that it's essential to defeating Hamas and winning the war.

Numerous governments and humanitarian aid organizations including the United Nations and the WHO have warned of the catastrophic humanitarian consequences of an invasion in the overcrowded enclave that's already been ravaged by military strikes, disease and famine.

"I made it clear that if they go into Rafah – they haven't gone in Rafah yet – 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 – that deal with that problem," Biden said in an interview with CNN broadcast Thursday.

"Civilians have been killed in Gaza as a consequence of those bombs and other ways in which they go after population centers," he said, when asked if the 2,000-pound bombs that the U.S. sends to Israel have killed civilians.

The Pentagon confirmed Wednesday that the administration paused the delivery to Israel of a shipment of 1,800 2,000-pound bombs and 1,700 500-pound bombs.

Biden and Secretary of Defense Lloyd Austin reiterated Washington's "ironclad" support for Israel, but Austin told lawmakers that "it's about having the right kinds of weapons for the task at hand" and that the U.S. wants to see Israel carry out "more precise" operations.

"A small diameter bomb, which is a precision weapon, that's very useful in a dense, built-up environment," he said, "but maybe not so much a 2,000-pound bomb that could create a lot of collateral damage."

Netanyahu remains undeterred, saying that Israel will "stand alone" and fight "with our fingernails" if U.S. weapons shipments stopped. Many other Israeli lawmakers attacked Biden and the U.S. for the announcement, despite the U.S. being Israel's single biggest supporter and source of military funding and weapons on the world stage.

Itamar Ben Gvir, Israel's far-right national security minister, posted on X simply writing: "Hamas [heart emoji] Biden."

Biden's warning marked the first time the president, a staunch supporter of Israel and a self-proclaimed Zionist, has paused or threatened to fully halt any arms shipments to the Jewish state. It's also important to note that the paused shipments in question may still be delivered at a later date, and that it reportedly does not apply to the $26.4 billion security assistance package for Israel already approved by Congress in April.

Israeli security experts say the pause won't impact planned operations in Rafah, while other analysts say the move is largely symbolic but aims to send a serious message. Israeli troops on Tuesday took control of the Gaza side of the vital Rafah border crossing and have been amassing troops there and carrying out strikes on some parts of the city.

"Despite the Biden administration withholding critical munitions from Israel in order to force the delay or halt of Israel's Rafah operation, it's unlikely that these munitions were the integral weapon required for Israel's planned operation," Avi Melamed, a former Israeli intelligence official and regional analyst, said.

Melamed argued that "Biden's statements embolden Hamas, Iran and put U.S. allies in the region at risk," but that he expects "slow and precise" operations by Israeli forces in Rafah, by which means he believes "Israel is likely to avoid a direct collision course with the Biden administration's latest position."

Clayton Allen, U.S. director at political risk firm Eurasia Group, called Biden's decision "a headline-grabbing move that has some eventual impact on Israeli capabilities," but added that it "doesn't hit at the bulk of U.S. assistance or really diminish what they can do in the coming weeks."

Others praised the move. Independent Sen. Bernie Sanders of Vermont said it must be a "first step."

"Our leverage is clear," Sanders said in a statement. "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."

Meanwhile, the nonprofit organization Democracy for the Arab World Now, or DAWN, which is focused on U.S. policy and human rights in the Middle East, said in a statement that the Biden administration's "suspension of massive bombs to Israel is an important but long overdue acknowledgement that Israel has been using American weapons to indiscriminately kill Palestinian civilians in violation of the most basic laws of war."

CNBC has contacted the Israel Defense Forces for comment.

Israel maintains that its war is against Hamas and that its forces endeavor to avoid civilian casualties. The Israel-Hamas war has killed more than 34,000 people in Gaza, according to Palestinian health authorities in the besieged enclave. The invasion was triggered by a Hamas-led terror attack on Israel on Oct. 7 that killed some 1,200 people there and took roughly 250 hostage, more than 100 of whom have been freed.

For Michael Koplow, chief policy officer of the Israel Policy Forum, the warning move by Biden represents a profound shift, and is something to be taken very seriously.

"For all of the times that Israel has seemed at an inflection point since October 7, it currently stands at a juncture that is genuinely perilous," Koplow wrote in a column on the forum's website Thursday.

"The U.S.-Israel relationship is showing increasingly more daylight through its cracks at the worst possible moment, and the Israeli attitude that it is mostly on the U.S. to seal those cracks is finding few buyers."