The Biden administration put a hold on a shipment of American-made ammunition to Israel last week amid concerns over an Israeli invasion of the Gazan city of Rafah, where more than a million Palestinian refugees are taking shelter, according to two Israeli officials.

The ammunition hold marks the first time the United States has stopped a shipment to the Israeli military since the Hamas attacks on Oct. 7, and is raising concerns inside Israel's government, officials told Axios.

The White House declined to comment on the decision, and the Pentagon, State Department, and Israeli Prime Minister Benjamin Netanyahu did not respond to questions. 

However, Biden is facing criticism over his support of Israel's actions in Gaza, and the administration asked in February that the Israeli military show proof that U.S.-made weapons are being used in accordance with international law. Israel signed a letter of its assurances in March.