Here's a list of domestic laws that were violated, to say nothing of international law:

The Foreign Assistance Act, which forbids the provision of assistance to a government which “engages in a consistent pattern of gross violations of internationally recognized human rights.”

Arms Export Control Act, which says countries that receive U.S. military aid can only use weapons for legitimate self-defense and internal security. Israel’s genocidal campaign in Gaza goes way beyond self-defense and internal security.

The U.S. War Crimes Act, which forbids grave breaches of the Geneva Conventions, including wilful killing, torture or inhuman treatment, wilfully causing great suffering or serious injury to body or health, and unlawful deportation or transfer, perpetrated by the Israeli Occupying Forces.

The Leahy Law, which prohibits the U.S. Government from using funds for assistance to units of foreign security forces where there is credible information implicating that unit in the commission of gross violations of human rights.

The Genocide Convention Implementation Act, which was enacted to implement U.S. obligations under the Genocide Convention, provides for criminal penalties for individuals who commit or incite others to commit genocide

https://www.commondreams.org/opinion/us-weapons-to-israel