The Biden administration has received nearly 500 reports alleging Israel used U.S.-supplied weapons for attacks that caused unnecessary harm to civilians in the Gaza Strip, but it has failed to comply with its own policies requiring swift investigations of such claims, according to people familiar with the matter.

At least some of these cases presented to the State Department over the past year probably amount to violations of U.S. and international law, these people said, speaking on the condition of anonymity because they are not authorized to discuss internal deliberations.