Tehran will face “severe consequences” for its large-scale missile attack on Israel Tuesday, the White House said, after the United States employed military force to help defend its closest Middle Eastern ally from Iranian fire for the second time in five months.

National security adviser Jake Sullivan said the barrage of nearly 200 ballistic missiles fired at Israel late Tuesday, only the second time Iran has launched a direct attack on the Jewish state, represented a “significant escalation.” He said President Joe Biden was closely tracking the developments, as spiraling violence threatens to undermine one of the U.S. leader’s chief foreign policy goals: preventing an all-out war across the Middle East.

“We are now going to look at what the appropriate next steps are to secure, first and foremost, American interests, and then to promote stability to the maximum extent possible as we go forward,” Sullivan told reporters at the White House. Officials said the attack had been largely ineffective, with one civilian death reported as initial assessments were made.

He declined to say what form the promised repercussions on Iran, already the object of extensive American sanctions, would take. “We have made clear that there will be consequences, severe consequences,” he said. “We will work with Israel to make that the case.”

Biden, speaking briefly to reporters, said the outcome of Iran’s strike was “a testament to intensive planning [between] the United States and Israel to anticipate and defend against a brazen attack.”

“Make no mistake,” he said. “The United States is fully, fully, fully supportive of Israel.”

The president spoke shortly after American destroyers in the eastern Mediterranean Sea shot down multiple missiles launched by Iran, according to U.S. defense officials who spoke on the condition of anonymity to discuss the operation. Pentagon press secretary Maj. Gen. Pat Ryder told reporters after the attack that two U.S. warships, the USS Bulkeley and USS Cole, fired about a dozen interceptors at inbound ballistic missiles, but said officials were still assessing how many of those struck a target. The comments suggested that Israel, with its extensive air defense network, shot down most of the incoming munitions on its own.

“Israel, with the active support of the United States and other partners, effectively defeated this attack,” said Secretary of State Antony Blinken. “We demonstrated, once again, our commitment to Israel’s defense.”

Vice President Kamala Harris, the Democratic nominee in November’s presidential elections, said she supported Biden’s decision to provide U.S. military support to Israel. She said the United States would “never hesitate to take whatever action is necessary to defend U.S. forces and interests against Iran and Iran-backed terrorists.”

Former president Donald Trump, the Republican nominee, said Biden and Harris were “leading us to the brink of World War III.” Speaking at a campaign event, he said their policies were to blame for current situation because “the so-called enemy doesn’t respect our country any longer.”

The incident echoes the events of April, when Iran launched a major missile and drone assault in retaliation for an Israeli strike that killed a senior Iranian military official in Syria. The assault was an ominous milestone for Israel, already engaged in a punishing war against Iranian-backed Hamas militants in the Gaza Strip and what until recent days had been a more limited conflict with Iranian-backed militant group Hezbollah in Lebanon.

This time, the exchange is overshadowed by a deepening engagement in Lebanon, where Israel has launched a series of major airstrikes over the last week and is now conducting ground operations against Hezbollah. The unfolding Israeli campaign, which aims to set conditions for allowing displaced Israelis to return to their homes in northern Israel, abruptly curtailed hopes for a near-term cease-fire between Israel and Hezbollah, Iran’s largest and most powerful militant client.

The situation underscores the Biden administration’s failure, despite months of diplomacy, to secure peaceful conclusions to the bloodshed in Gaza and, now, in Lebanon. Iranian officials said Tuesday’s attack was self-defense following a series of recent high-level assassinations, including Hamas political chief Ismail Haniyeh, killed by a bomb in Tehran in July, and Hezbollah leader Hasan Nasrallah and Iranian brigadier general Abbas Nilforoushan, who were killed in a Beirut airstrike last month.

Over the last year, the Biden administration has repeatedly cautioned the government of Prime Minister Benjamin Netanyahu in the wake of deflected attacks by adversaries, including Iran, to “take the win” and avoid fueling further escalation by conducting a major counterstrike. It is likely to do so again in this instance.

U.S. officials say they are committed to defending Israel when the country faces external attacks but does not intend to conduct offensive operations in Lebanon or other countries.

U.S. officials said that they detected signs of an imminent Iranian attack in the hours before it was launched Tuesday, but there was no direct or indirect warning from Iran’s government ahead of time.

During Iran’s April attack, a pair of U.S. destroyers positioned off Israel in the Mediterranean shot down a handful of ballistic missiles; a Patriot missile defense battery shot down a missile over Iraq; and American jets from the 494th and 335th fighter squadrons downed dozens of munitions headed for Israel. This time, the U.S. role appeared to have been even more limited.

The United States’ role in providing intelligence, rather than military might, may have proven more significant Tuesday. Israel’s military said before the strike that the United States had alerted Israel about Iranian plans to launch an attack.

U.S. officials, speaking on the condition of anonymity to discuss sensitive assessments, said they continue to believe that Iran does not want a broader war with Israel — one that it probably cannot win — even after Tuesday’s attack.

Iran’s new president, Masoud Pezeshkian, said before the deaths of Nasrallah and Nilforoushan that his country had postponed an earlier retaliation for Haniyeh’s killing because of Washington’s promise that a cease-fire between Israel and Hezbollah was days away, a notion he portrayed as a deliberate American attempt to mislead.

State Department spokesman Matthew Miller said the Biden administration would continue to work to stave off such a conflict.

“There have been a number of times in the past 12 months where it looked like we might reach such a conflagration,” he told reporters, referring to the war kicked off by the Hamas-led attack into Israel on Oct. 7, 2023.

Iran’s missile and drone attack in April was one of such moments, Miller said. “And the United States, through a complex combination of deterrence and diplomacy, has been able to prevent such an outbreak of full-scale war, and we will continue to try and prevent an outbreak of full-scale war in the days and weeks ahead.”

Shane Harris and Abigail Hauslohner contributed to this report.