WASHINGTON (AP) — The U.S. paused a shipment of bombs to Israel last week over concerns that Israel was approaching a decision on launching a full-scale assault on the southern Gaza city of Rafah against the wishes of the U.S., a senior administration official said Tuesday.

The shipment was supposed to consist of 1,800 2,000-pound (900-kilogram) bombs and 1,700 500-pound (225-kilogram) bombs, according to the official, who spoke on the condition of anonymity to discuss the sensitive matter, with the focus of U.S. concern being the larger explosives and how they could be used in a dense urban setting. More than 1 million civilians are sheltering in Rafah after evacuating other parts of Gaza amid Israel’s war on Hamas, which came after the militant group’s deadly attack on Israel on Oct. 7.

The U.S. has historically provided enormous amounts of military aid for Israel. That has only accelerated in the aftermath of Hamas’ Oct. 7 attack that killed some 1,200 in Israel and led to about 250 being taken captive by militants. The pausing of the aid shipment is the most striking manifestation of the growing daylight between Israel Prime Minister Benjamin Netanyahu’s government and the administration of President Joe Biden, which has called on Israel to do far more to protect the lives of innocent civilians in Gaza.