Israel-Gaza updates: 22, including 18 children, reported dead in Rafah strikes

As Israel on Monday weighed its response to Iran’s weekend attack, the U.S. is privately telling officials there: If Israel strikes back militarily, it will do so alone.

It's an unusual message for a close ally that's spent decades receiving more U.S. military aid than any other country in the world and whose relationship with America is often described as "ironclad."

But after months of Israel acting on its own in Gaza -- and facing tough criticism from the U.S. and other allies that its military operations have gone too far – the Biden administration made clear the U.S. wouldn't participate in offensive military operations against Iran, fearing a broader war in the Middle East.

"We believe Israel has freedom of action to protect itself and defend itself," a senior administration official told reporters shortly after Iran's attack ended. "That's a long-standing policy, and that remains."

When asked by a reporter if the U.S. would help Israel counter with offensive military operations, the official said no.

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-ABC News’ Anne Flaherty

President Joe Biden on Monday touted the "unprecedented military effort to defend Israel" against Iran, declaring "together with our partners we defeated that attack."

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Biden says US 'committed to Israel's security'

President Joe Biden addressed Iran's retaliatory attack against Israel while the prime minister of Iraq was visiting the White House.

ABCNews.com

In his first on-camera remarks since this weekend's Iranian strike, the president stressed that "the United States is committed to Israel's security."

"We're committed to a cease-fire that will bring the hostages home and preventing the conflict from spreading beyond what it already has" the president told reporters in the Oval Office ahead of his meeting with the Iraqi prime minister. "We are also committed to the security of our personnel and our partners in the region, including Iraq."

A senior Israeli Air Force official said that the normalization of relations with Middle Eastern countries "served us during this crucial time" this weekend.

"It has to be clear that real assets" provided Israel with "information" and an "early warning," and the "majority" of that intelligence came from the coalition, the senior Israeli Air Force official said at a Monday briefing.

In terms of the types of drones and missiles used by Iran in the Saturday night attack, the official said Israel did not face any types of missiles that it had not shot down during attacks in recent months by Iranian proxies.

The official confirmed that only "a handful" of ballistic missiles fired by Iran were not intercepted.

"Five, more or less, managed to penetrate," the official said.

He said Israel's "strategic investment" in air defense capabilities, made years ago, had paid off, and called Israel shooting down nearly all missiles a "historic success."

The official was asked if Israel would be able to withstand a similar level of attack from Iran, without the support of allies such as the U.S.

"It would be more challenging,” the official conceded, but added that Israel has capabilities "to face this kind of challenge."

-ABC News’ Tom Soufi Burridge

Israel on Saturday demonstrated its "military superiority" against Iran while also showcasing its partnership with military allies, including the United States, John Kirby, spokesperson for the White House National Security Council, said Monday.

Israel said Sunday about 99% of the missiles and drones launched by Iran were intercepted by Israel and its allies, a defense that Kirby called a "tremendous success."

"I think it did show, did demonstrate that Iran is not the power that it purports to be, that it doesn't have that same military superiority," Kirby said on "Good Morning America."

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White House urges caution as Israel weighs response to Iran missiles

White House national security spokesperson John Kirby answers questions about the nation's response to rising tensions between Israel and Iran.

ABCNews.com

Israeli Prime Minister Benjamin Netanyahu is expected on Monday to reconvene his war cabinet, a body that met on Sunday without deciding on a response to Iran's attack. And President Joe Biden and his G7 counterparts on Sunday released a statement urging Iran to cease its attacks.

"With its actions, Iran has further stepped toward the destabilization of the region and risks provoking an uncontrollable regional escalation," the G7 leaders' statement said. "This must be avoided."

The United States would not participate in an Israeli response, if the country decides to strike back against Iran, U.S. defense and security officials said on Sunday.

But the final decision on whether Israel strikes back will fall to Netanyahu, Kirby said Monday.

"The president was also clear, as he has been throughout, that we do not seek a wider war in the region and we don't seek conflict with Iran," he said.

-ABC News' Kevin Shalvey