US National Security Adviser Jake Sullivan said on Tuesday that the United States will work with Israel to ensure that Iran faces "serious consequences" for its missile attack on Israel, which came in response to the recent Israeli escalation.

"There will be serious consequences for this attack, and we will work with Israel to prove that," Sullivan told reporters at the White House.

President Biden said the United States was in “active discussions” with Israel about a response. “The United States fully and comprehensively supports Israel,” he said.

Media reports say Iran fired at least 180 rockets at Israel. Iran’s Islamic Revolutionary Guard Corps said the attack was in response to Israel’s assassination of Hamas political bureau chief Ismail Haniyeh in Tehran on July 31, as well as the assassinations of Hezbollah Secretary-General Hassan Nasrallah and Abbas Nilforoushan, the Revolutionary Guards commander who was killed alongside Nasrallah.

The Iranian Revolutionary Guard claimed that 90 percent of the missiles hit their targets, while Israel said most were intercepted. Videos have emerged on social media showing the missiles making impact. So far, no Israelis have been reported killed, but a Palestinian in the occupied West Bank was killed when shrapnel from an intercepted rocket fell on Jericho.

The United States said it helped Israel intercept some of the Iranian missiles and portrayed the defense as a success. Sullivan said the Iranian attack "appears to have been defeated and ineffective."

“We are proud of the actions we have taken alongside Israel to protect and defend Israel,” Sullivan added. The attack came a day after the Pentagon announced it would send “a few thousand” troops to the Middle East to prepare to defend Israel if necessary.

“This was a brazen and unacceptable attack by Iran, and every nation in the world should join us in condemning it,” State Department spokesman Matthew Miller said at a press briefing on Tuesday. “Secretary of State Blinken joined President Biden, Vice President Harris, and other members of the President’s national security team in monitoring this attack as it unfolded, as well as our response. As the President has made clear, our support for Israel’s security is strong, and we will continue to stand with the people of Israel at this critical moment.”

Asked about what he called Iran’s “brazen escalation,” without mentioning Israel’s escalation in the past three weeks, Miller said: “They’ve certainly done things to expand the conflict, but if you look at the actions they’ve taken, they’ve brought terrorists to justice, terrorists who have attacked Israeli civilians. If you look at what Iran did today, it was an attack on a country that is working to protect itself from terrorist groups; so there’s a difference between the actions that we’ve seen Israel take to defend its civilians, and what Iran has done.”

The Iranian attack came more than a week after a dramatic escalation in Israel’s bombing campaign in Lebanon, which has killed more than 1,000 people since September 23, the majority of them civilians. Despite claims by Biden administration officials that they want to see a ceasefire in Lebanon, the United States has supported Israel’s escalation and is now prepared to defend it from any consequences it may face.

Iran has indicated it is done attacking Israel but has warned there will be a "crushing response" if Israel retaliates. Israeli officials have made clear they are planning to respond.

"There will be consequences," said Israeli military spokesman Daniel Hagari. "Our defensive and offensive capabilities are at the highest level of readiness. Our operational plans are ready. We will respond wherever, whenever and however we choose, in accordance with the directives of the Israeli government."

Israeli Prime Minister Benjamin Netanyahu said Iran would “pay” for the attack. “This evening, Iran made a grave mistake — and it will pay for it,” he told a meeting of his security cabinet. “The regime in Tehran does not understand our determination to defend ourselves and exact a price from our enemies.”

Security analysts and former officials say Washington gave Israel more freedom to respond forcefully to Tuesday's Iranian missile barrage than it did in April, when its response to the previous Iranian attack was a largely symbolic strike against an air defense facility in Iran.

They say Israel was concerned that issuing too intense a response would prompt Iran to order its proxy militias — particularly Hezbollah in Lebanon — to retaliate on a massive scale.

But after launching a bombing campaign that killed Hezbollah’s leader and other commanders last week, along with an overnight ground invasion on Tuesday, Israel has weakened Hezbollah and stripped Iran of much of its deterrent power against a broader Israeli attack, Danny Citrinovitch, a retired Israeli intelligence officer who specializes in Iran, told The New York Times.

"Israel has more freedom in the Iranian context than it did last April, as there is no longer a fundamental threat that Hezbollah will join in," Citrinovic said.

The Biden administration may urge Israel to rein in its response, but with the U.S. election fast approaching, U.S. officials are likely to have less influence than they did in April, experts say.

"This is an escalation whose end is difficult to predict. Israel's action will certainly lead to another Iranian response. It seems that we are at the beginning of a strong confrontation between us and the Iranians," Citrinovic said.

But after Iran fired about 180 rockets in an attack that lasted about half an hour, the challenge for Israel was not whether to attack Iran but how hard to respond, said Yaakov Amidror, a retired major general who served as national security adviser to Benjamin Netanyahu.

The only question, said Gen. Amidror, is “how much can we hurt them compared to their ability to hurt us.” He added that he believes the damage Israel has inflicted on Hezbollah has reduced the threat from Iran’s proxies. Gen. Amidror added that an attack on Iran’s nuclear facilities — a long-standing fear for Israel, which fears Tehran could acquire a nuclear weapon — “must be taken into account.”

Former Israeli Prime Minister Naftali Bennett wrote on social media that Israel faced “the greatest opportunity in the past 50 years” to change the face of the region. “We must act now to destroy their nuclear project, destroy their main energy facilities and decisively strike this terrorist regime,” Bennett said of Iran. “The tentacles of this octopus have been badly wounded — now is the time to aim for the head.”