The U.S. paused a shipment of bombs to Israel over worries about Israel nearing a decision to launch a wide-ranging military offensive on the city of Rafah, in the southern Gaza Strip, which U.S. President Joe Biden opposes, according to a senior administration official.

The delivery was supposed to contain 1,800 2,000-pound (907-kilogram) bombs and 1,700 500-pound bombs, said the official, who was granted anonymity to discuss a sensitive matter, late on Tuesday night.

The official added that the administration is worried about the damage the larger bombs could inflict on dense urban settings like Rafah, where more than 1 million displaced Palestinians are sheltering. The U.S. has not made a final decision about how to proceed with the shipment, according to the official.