The State Department "has informally notified Congress of an $8 billion proposed sale of munitions to support Israel's long-term security by resupplying stocks of critical munitions and air defense capabilities," the official said, speaking on condition of anonymity.

The preliminary notification gives congressional committees an opportunity to scrutinize the proposed sale, ahead of a formal notification to Congress.

The weapons package includes medium-range air-to-air missiles to defend against aerial threats; Hellfire AGM-114 missiles; 155mm projectile artillery shells for long-range targeting; and 500-pound warheads, the official said.

The Biden administration has provided Israel with billions in arms aid since Israeli forces launched a massive attack on Hamas militants in Gaza response to their deadly October 7 surprise attack in southern Israel.

The outgoing US president has repeatedly vowed "ironclad" support for Israel.

But against the backdrop of a rising Palestinian death toll -- now over 45,700, according to the Hamas-run health ministry in Gaza -- and the increasingly dire conditions facing civilians, the US support has become a sensitive political issue.

Many Arab and Muslim Americans, joined by some progressives, vowed not to vote for Biden in the November presidential election unless he halted the weapons aid to Israel. Students on dozens of US campuses protested the aid.

But the official said Saturday that "the president has made clear Israel has a right to defend its citizens, consistent with international law and international humanitarian law, and to deter aggression from Iran and its proxy organizations. We will continue to provide the capabilities necessary for Israel's defense."

Donald Trump, an outspoken supporter of Israel, said during the US presidential campaign that if elected he would quickly end the Gaza war, although he did not explain how.

United Nations officials say as many as 70 percent of those killed in the Gaza hostilities have been women or children, and aid agencies have described harrowing conditions facing civilians.

The Biden administration has urged Israel to increase humanitarian aid, but after threatening to curb arms shipments if the aid situation did not improve, it declined in November to do so.

Recent Israeli airstrikes in Gaza have killed several dozen people, according to the Gaza health ministry.