The Biden administration is delaying shipments of ammunition that were expected to be sent to Israel, according to three U.S. officials.

The Biden administration has been trying to pressure Israel to hold off on a full-scale invasion of Rafah until it has a plan to protect the million civilians now living there.

The Air Force has been told by the White House’s National Security Council to pause shipments of ammunition deliveries specifically from Dover Air Force Base, according to a U.S. official. The NSC was behind the decision to pause the munitions, a second U.S. official confirmed.

The National Security Council did not immediately respond to a request for comment.

-ABC News' Martha Raddatz, Anne Flaherty, Matt Seyler and Ben Siegel

House Speaker Mike Johnson and Majority Leader Steve Scalise have publicly accused the Biden administration of withholding aid to Israel following reports that some aid shipments have been halted. Johnson said that the Biden administration as recently as Friday had assured his staff that there would be "no delay" in assistance to Israel.

Johnson said he received a report this morning from on the ground in Israel that said "a shipload of munitions and precision weapons, which are to be used to help protect civilians and Rafah, is being withheld."

In a letter to President Joe Biden, Senate Republicans Jodi Ernst and Ted Budd said they are "shocked" and "deeply concerned" that the Biden administration failed to notify Congress before withholding ammunition to Israel.

"If these reports are true, then you have once again broken your promise to an American ally," they said.

-ABC News' Lauren Peller and Shannon Crawford

In his first comments since Israel's offensive into Rafah began, Prime Minister Benjamin Netanyahu said that Hamas' cease-fire proposal on Monday was "intended to torpedo the entry of our forces into Rafah."

"It did not happen. As the War Cabinet unanimously determined, the Hamas proposal is very far from Israel's necessary requirements," Netanyahu said.

"I instructed the working-level delegation that went to Cairo: continue to stand firm on the conditions necessary for the release of our abductees, continue to stand firm on the essential requirements for guaranteeing Israel's security," Netanyahu said.

-ABC News' Will Gretsky

Israeli tanks controlled Gaza's Rafah border crossing early Tuesday, as military officials accused Hamas of using the crossing for "terrorist purposes."

"Following intelligence that indicated that the Rafah Crossing in eastern Rafah was being used for terrorist purposes, IDF troops managed to establish operational control of the Gazan side of the crossing," Israel Defense Forces officials said in a statement.

Mortars had on Sunday been fired "from the area," killing four IDF soldiers, the Israeli military said.

A video and photos taken by the Israeli military and released Tuesday appeared to show several Israeli tanks operating on the Gazan side of the border.

-ABC News' Kevin Shalvey

Although the Biden administration said it expected the Kerem Shalom and Rafah gates to be at least partially opened for humanitarian aid by Wednesday, the State Department was much less optimistic. However, the U.S. vowed it would continue to press Israel to get both portals up and running again.

While Kerem Shalom reopened Wednesday, aid had not been allowed to pass through because of "logistical and security concerns on the ground," State Department spokesperson Matt Miller said during a briefing Wednesday. He also said fuel had not been able to enter Gaza through Rafah.

"We think it's critical that Rafah be open for fuel because without fuel deliveries into Rafah, humanitarian assistance that comes in through Kerem Shalom can't actually be delivered. The two are critically linked," Miller said. "We're continuing to push for that to happen."

Miller didn’t provide any updated timeline on when the U.S. expected the crossings would be functional again, but said it was imperative that Israel act to increase the amount of aid allowed into Gaza following what he described as a "fairly dramatic dip" this week.

"When it comes to the level of humanitarian assistance, the results as they are today are just unacceptable. There's no other way to put it," Miller lamented.

He continued, "We are making quite clear to the government of Israel that we need to see those decreases reversed. We need to get back to where we were, and we need to see the levels continue to increase and see those sustained, and that is why we need to see Kerem Shalom and Rafah opened."

-ABC News' Shannon Crawford