The White House last week paused a shipment of weapons to Israel, as Israeli leaders neared a decision to launch an operation in the southern Gaza city of Rafah, a senior administration official said Tuesday.

Defense Secretary Lloyd Austin confirmed Wednesday in testimony to Congress that “we’ve paused one shipment of high-payload munitions.” Austin said the administration is reviewing some near-term security assistance to Israel in the context of unfolding events in Rafah. Several senators were upset about the delay, including Sen. Lindsey Graham, who called the move “obscene” and “absurd.”

Austin told the senators that a final decision has not been made on what to do with the shipment, but there are things the administration is looking at when it comes to Rafah. Austin said 2,000-pound bombs can cause a lot of collateral damage and the U.S. is looking to protect the civilians in the city.

Meanwhile, Israel’s military announced Tuesday the launch of “targeted strikes” against Hamas in Rafah, which Israel has said is Hamas’ last stronghold, after Israel’s War Cabinet approved a military operation in the city.

The U.S. has long held that Israel shouldn’t launch such a major ground operation in Rafah, where more than 1 million people are taking shelter after fleeing other parts of Gaza. But the United States’ concerns in discussions with Israel about addressing humanitarian needs in Rafah and how to approach Hamas have not been sufficiently addressed, the senior administration official said. When Israeli leaders appeared close to a decision on Rafah, the Biden administration began to review upcoming transfers of weapons that could be used in Rafah, and as a result, paused one shipment last week, the official said.