President Joe Biden has grown increasingly frustrated behind the scenes with his Israeli counterpart, Benjamin Netanyahu, telling advisers and others that the prime minister is ignoring his advice and obstructing efforts to alleviate the humanitarian crisis in Gaza, according to people familiar with the matter.

So far, Biden has stopped short of directly criticizing Netanyahu in public. But he has become increasingly critical of Israel’s tactics, saying last week he believes the campaign in Gaza is “over the top,” one of his sharpest condemnations to date of the military effort against Hamas.

In private, Biden has been more willing to offer unvarnished thoughts on Netanyahu, including his deep irritation that the Israeli prime minister has not followed through on American recommendations to de-escalate military tactics in Gaza. Some officials now wonder how much longer Biden will withhold public criticism of Netanyahu as the war rages on.

The president’s comments last week on Israel’s tactics reflected sentiments he has been voicing behind the scenes for a while, one person familiar with the matter said. US officials had hoped that by January, Israel would have transitioned to a lower-intensity, hyper-localized targeting campaign.

The tension between the Biden administration and Netanyahu’s government has only intensified in recent days over Israel’s preparations for a ground incursion into Rafah, where thousands of displaced Palestinians have fled over the course of the war.

US officials have been direct in their conversations with Israeli counterparts that the estimated 1.3 million people currently in Rafah simply “have nowhere to go,” according to a senior administration official. The Biden administration is highly skeptical about whether Netanyahu’s direction to Israel’s military for an “evacuation of the population” out of Rafah before Israel forces go in is even remotely feasible.

“We have made very clear that an operation under current conditions is not something that we could envision,” the US official said.

In the call, Biden told Netanyahu an operation in Rafah “should not proceed” without ensuring the safety of the more than 1 million people sheltering there, the White House said.

Biden has long had his differences with Netanyahu and officials acknowledge their relationship is complex. But in recent days, a series of actions and comments have angered some American officials, who like Biden are losing patience with Netanyahu’s resistance to US advice and recommendations.

That includes publicly rejecting as “crazy” a Hamas counter proposal on a deal to release hostages and pause the fighting, even as Secretary of State Antony Blinken was in the region to try to advance the agreement. The majority of a 45-minute phone call between Biden and Netanyahu on Sunday was about the hostages deal, according to an official.

Biden and his team have also been irritated by Netanyahu’s public rejections of a two-state solution, long a lynchpin of American policy in the region.

Biden and Netanyahu, who have known each other for more than four decades, have found themselves frequently at odds, both before the October 7 Hamas attacks and after. Biden has bemoaned Netanyahu’s far-right governing coalition and told donors last year that his counterpart’s political predicament was making it difficult for the prime minister to alter his approach to Gaza.

The president is also under pressure from progressive Democrats to do and say more about the suffering of the Palestinians in Gaza, including through now-frequent protests at his public events.

Still, White House officials have long said the president believes any differences with his counterpart are best aired behind the scenes rather than in public.

Biden has made light of his disagreements with Netanyahu, recounting an inscription he wrote on an old photograph of the two men: “Bibi, I love you, but I don’t agree with a damn thing you have to say.”

“It’s about the same today,” Biden said in December.

Since then, however, frustrations have only mounted over Israel’s military campaign and tactics when it comes to negotiating a deal to secure the release of hostages.

Biden offered his Israeli counterpart and the people of Israel his unwavering support in the immediate aftermath of the October 7 attack, even flying to the war zone to show what he said was his and the United States’ unequivocal support for their ally.

Netanyahu, meanwhile, offered Biden praise over the weekend as the president was combatting questions about his age and mental acuity. In an interview, the Israeli prime minister said he found Biden “very clear, very focused” when asked about special counsel Robert Hur’s description on Biden as a “well-meaning, elderly man with a poor memory.”

In an interview with ABC News, Netanyahu said he’s had over a dozen “extended phone conversations” with Biden. “He also came on a visit to Israel during wartime, which was a historic first, and I found him very clear and very focused,” Netanyahu said.

“We managed to agree on the war aims and on many things. Sometimes disagreements, but they weren’t born of a lack of understanding on his part or on my part,” Netanyahu said.