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 bombs and 1,700 500-pound 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.

President Joe Biden's administration in April began reviewing future transfers of military assistance to Israel as Prime Minister Benjamin Netanyahu's government appeared to move closer toward an invasion of Rafah, despite months of opposition from the White House. The official said the decision to pause the shipment was made last week and no final decision had been made yet on whether to proceed with the shipment at a later date.

The State Department is separately considering whether to approve the continued transfer of Joint Direct Attack Munition kits, which place precision guidance systems onto bombs, to Israel, but the review didn't pertain to imminent shipments.