The US government considers it possible that Israel may have used weapons provided by Washington to violate international humanitarian law in the Gaza Strip.
Due to the situation in the war zone, it is difficult to assess individual incidents or make conclusive findings,
"It is often difficult to make swift, definitive assessments or determinations on whether specific U.S. defense articles or services have been used in a manner not consistent with international law," according to the report by the US State Department, which was submitted to the US Congress on Friday afternoon after a delay.
"However, there have been sufficient reported incidents to raise serious concerns," the report said.
The State Department said it has received reports from several credible UN and non-governmental sources of possible human rights abuses by Israeli forces, it added.
Given Israel's significant reliance on US defence equipment, "it is reasonable to assess that defense articles covered under NSM-20 have been used by Israeli security forces since October 7 in instances inconsistent with its IHL [International Humanitarian Law] obligations or with established best practices for mitigating civilian harm," the report stated.
At the beginning of February, President Joe Biden had demanded written assurances from foreign governments that military aid from the US does not violate international law.
The US State Department was to obtain "credible" assurances from the countries concerned within 45 days. This concerns countries whose US aid has been authorized by Congress and which are currently engaged in an armed conflict, including Israel.
The US State Department had to inform Congress of the process in a report. The deadline for this was originally Wednesday, but the US State Department had announced a delay of a few days without giving more precise reasons.
The report has only now been published.
At the time, Biden's statement said that if the assurances of the countries concerned regarding compliance with international law were not provided within this period, military support would be stopped.
It also listed the handling of humanitarian aid, stating that "the recipient country will facilitate and not arbitrarily deny, restrict, or otherwise impede, directly or indirectly, the transport or delivery of United States humanitarian assistance and United States Government-supported international efforts to provide humanitarian assistance."
The report says Israeli officials have stated that Israel is complying with international humanitarian law and is continuing to increase its efforts to minimise harm to civilians.
The ministry emphasised that a country's general commitment to international humanitarian law is not necessarily contradicted by individual violations, as long as the country takes appropriate steps to investigate them.
CNN had previously reported, citing a US government representative, that there was disagreement in the US State Department as to whether Israel's commitments should be accepted as "credible and reliable."
Criticism also came from Biden's own party. Several media outlets quoted Democratic Senator Chris Van Hollen as saying that the report had "a big gap" with regard to the specific use of US weapons. The ministry had only come to a general conclusion.
However, it "it fails to do the hard work of making an assessment and ducks the ultimate questions that the report was designed to determine with respect to compliance with international law," van Hollen said.
Fighters from Hamas and other Palestinian Islamist groups carried out a devastating attack in Israel on October 7 last year, killing 1,200 people including around 800 civilians. Since then, Israel has been waging war against Hamas in the Gaza Strip.
The high number of civilian casualties in the Gaza war and the humanitarian catastrophe for the Palestinian civilian population have triggered sharp international criticism of Israel's actions.
As Israel's most important ally, the US has long been urging the government in Jerusalem to step up protection of the civilian population and allow more humanitarian aid into the Gaza Strip.