The incidents – some of which might have violated international humanitarian law, according to the sources – have been recorded since Oct. 7, 2023, when the Gaza war started. They are being collected by the State Department’s Civilian Harm Incident Response Guidance, a formal mechanism for tracking and assessing any reported misuse of US-origin weapons.

State Department officials gathered the incidents from public and non-public sources, including media reporting, civil society groups and foreign government contacts.

The mechanism, which was established in August 2023 to be applied to all countries that receive US arms, has three stages: incident analysis, policy impact assessment, and coordinated department action, according to a December internal State Department cable reviewed by Reuters.

None of the Gaza cases had yet reached the third stage of action, said a former US official familiar with the matter. Options, the former official said, could range from working with Israel’s government to help mitigate harm, to suspending existing arms export licenses or withholding future approvals.

The Washington Post first reported the nearly 500 incidents on Wednesday.

The administration of President Joe Biden has said it is reasonable to assess that Israel has breached international law in the conflict, but assessing individual incidents was “very difficult work”, State Department spokesperson Matthew Miller told reporters on Wednesday.

“We are conducting those investigations, and we are conducting them thoroughly, and we are conducting them aggressively, but we want to get to the right answer, and it’s important that we not jump to a pre-ordained result, and that we not skip any of the work,” Miller stated, adding that Washington consistently raises concerns over civilian harm with Israel.

The administration of President Biden has long noted it is yet to definitively assess an incident in which Israel has violated international humanitarian law during its operation in Gaza.

John Ramming Chappell, advocacy and legal adviser at the Center for Civilians in Conflict, said the Biden administration “has consistently deferred to Israeli authorities and declined to do its own investigations”.

“The US government hasn’t done nearly enough to investigate how the Israeli military uses weapons made in the United States and paid for by US taxpayers,” he added.

The civilian harm process does not only look at potential violations of international law but at any incident where civilians are killed or injured and where US arms are implicated, and looks at whether this could have been avoided or reduced, said one US official, who spoke on condition of anonymity.

A review of an incident can lead to a recommendation that a unit needs more training or different equipment, as well as more severe consequences, the official added.

Israel’s military conduct has come under increasing scrutiny as its forces have killed more than 43,000 Palestinians in Gaza, according to the enclave’s health authorities.