From another comment:
POTUS has the power to pause military equipment shipments. Biden did exactly this with Israel, as have a few other presidents in other situations. The current congressional Republicans put forward legislation to prevent POTUS from being able to do that. (I'm not sure whether that bill got anywhere or not.) Biden said he would veto such a bill.
Foreign military aid to Israel is supplied as of the terms of the United States - Israel Strategic Partnership Act of 2014, a ten year agreement to supply Israel with certain military aid, which was signed by the US and Israel in 2016, and which took effect in 2018. That was passed by Congress. POTUS does not have the power to unilaterally end that agreement; Congress does.