The US is reported to have made more than 100 weapons sales to Israel, including thousands of bombs, since the start of the war in Gaza, but the deliveries escaped congressional oversight because each transaction was under the dollar amount requiring approval.

The Biden administration has become increasingly critical of the conduct of Israeli military operations in Gaza and the failure to allow in meaningful amounts of humanitarian aid, with the death toll now over 30,000 and with famine looming. But it has kept up a quiet but substantial flow of munitions to help replace the tens of thousands of bombs Israel has dropped on the tiny coastal strip, making it one of the most intense bombing campaigns in military history.

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The Washington Post reported that administration officials informed Congress of the 100 foreign military sales to Israel in a classified briefing. Few details are known of the sales, because keeping each one small meant their contents remained secret, but they are reported to have included precision-guided munitions, small diameter bombs, bunker busters, small arms and other lethal aid.

The Arms Export Control Act makes significant exceptions for arms sales to close allies – a limit of $25m for ‘major defense equipment’, defined as big-ticket items that require a lot of research and development, but the limit rises to $100m for other “defense articles” like bombs.

“This doesn’t just seem like an attempt to avoid technical compliance with US arms export law, it’s an extremely troubling way to avoid transparency and accountability on a high-profile issue,” Ari Tolany, director of the security assistance monitor at the Centre for International Policy thinktank, said.

She added that, in exploiting the loophole, the Biden administration was following the steps of its predecessor.

“They’re very much borrowing from the Trump playbook to dodge congressional oversight,” Tolany said. The state department office of the inspector general found that between 2017 and 2019, the Trump administration had made 4,221 below-threshold arms transfers to Saudi Arabia and the United Arab Emirates, worth an estimated total of $11.2bn.

The under-the-radar deliveries made by the Biden administration to Israel were additional to the three major military sales that were made public since the start of the war: $320m in precision bomb kits in November and 14,000 tank shells costing $106m and $147.5m of fuses and other components needed to make 155mm artillery shells in December. The December deliveries of tank and artillery shells also sidestepped congressional scrutiny because they were made under an emergency authority.

In defending its continued arms sales to Israel, despite ever more public misgivings about its conduct of the Gaza war, the administration has argued that they are part of the US’s basic commitment to Israel’s self defence.

“We continue to support Israel’s campaign to ensure that the attacks of 7 October cannot be repeated. We have provided military assistance to Israel because it is consistent with that goal,” Matthew Miller, the state department spokesperson, said. “We support Israel’s legitimate military campaign consistent with international humanitarian law.”

The state department has been vague about how much effort it is putting into assessing whether Israeli forces are committing war crimes. A process called Civilian Harm Incident Response Guidance (CHIRG) was set up in September last year, before the Gaza war, to make assessments of the use made of US armaments, and Israel’s military operations are under review, but the process is slow and does not commit the administration to taking remedial action.

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“The revelation that the administration has made 100 arms sales to Israel since the beginning of its attacks on Gaza – most of them hidden from public view – makes a mockery of its rhetoric about pressing the Netanyahu government to do more to protect civilians,” William Hartung, an arms industry expert at the Quincy Institute for Responsible Statecraft. “Israel’s attacks on homes, hospitals – even on civilians waiting to receive humanitarian aid – are clear violations of US and international law, not to mention stated Biden administration policy.”

Hartung added: “It’s long past time for the administration to cut off arms supplies to Israel as leverage to stop the slaughter in Gaza. To do otherwise is both immoral and strategically bankrupt.”