The “significant” role the U.S. played in helping Israel fend off Iran’s aerial assault on Tuesday came just hours after Secretary of Defense Lloyd Austin assured Israeli Defense Minister Yoav Gallant that the U.S. had “increased force readiness” and stood ready.

“This is a significant escalation by Iran,” White House National Security Advisor Jake Sullivan told reporters Tuesday. “It is equally significant that we were able to step up with Israel and create a situation in which no one was killed in this attack in Israel.”

The comments were made following massive missile strike fired by Iran in which some 180 missiles were fired at Israel.

According to Iranian state media, the Iranian Revolutionary Guard Corps (IRGC) said the attack was in retaliation for the Friday assassination of Hezbollah leader Hassan Nasrallah, who was killed alongside IRGC commander and military advisor Brig. Gen. Abbas Nilforushan, as well as Ismail Haniyeh, the leader of Hamas who was killed in July during a visit to Tehran.

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“In response to the martyrdom of Ismail Haniyeh, Seyyed Hassan Nasrallah and Martyr Nilfroshan, we targeted the heart of the occupied territories,” the IRGC said in a statement reported by Iranian media. “If the Zionist regime reacts to Iran’s operations, it will face crushing attacks.”

Following the attacks, Israel closed its airspace, residents in Tel Aviv and Jerusalem were ordered to shelter in place and the Israeli security cabinet said it would convene Tuesday night in a bunker in Jerusalem, according to Israeli news outlet the Jerusalem Post.

It remains unclear if Iranian missiles had made contact with any targets, though the Israeli Defense Force (IDF) told Fox News Digital that no casualties were yet known.

In a statement to Fox News, a U.S. defense official said, “[In] accordance with our ironclad commitment to Israel’s security, U.S. forces in the region are currently defending against Iranian-launched missiles targeting Israel. 

“Our forces remain postured to provide additional defensive support and to protect U.S. forces operating in the region,” the official added.

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Earlier on Tuesday, the Pentagon said in a readout regarding the second call Austin has held with Gallant in the last 24 hours, that the secretary “made it clear that the United States is well-postured to defend U.S. personnel, allies, and partners in the face of threats from Iran and Iran-backed terrorist organizations and is determined to prevent any actor from exploiting tensions or expanding the conflict in the region.”

Three U.S. guided-missile destroyers have been positioned off the eastern Mediterranean to help defend Israel, including the USS Arleigh Burke, USS Bulkeley and USS Cole — which reportedly played a closely coordinated role in defending against the Iranian attack on Tuesday.

“Today, Iran launched nearly 200 ballistic missiles towards targets in Israel. The United States military coordinated closely with the Israeli Defense Forces to help defend Israel against this attack,” Sullivan said.  “U.S. naval destroyers joined Israeli Air Defense units in firing interceptors to shoot down inbound missiles.”

In April, during the last major attack that Iran levied at Israel when it fired more than 300 drones and missiles, the USS Arleigh Burke and the USS Carney shot down more than 81 attack drones and at least six ballistic missiles using guided-missile destroyers.

The ballistic missiles were shot down using the SM-3 ballistic missile interceptors from the ships that were also positioned in the eastern Mediterranean at the time. The SM-3 has a range of up to 1,550 miles.

Israel has several of its own defense systems outside of what its offshore allies provide, including the infamous Iron Dome which is designed to intercept short-range rockets and artillery shells fired from distances of two to 43 miles away.

But it also has systems that are capable of stopping missiles fired from greater distances, like its Arrow Missile Defense System, which can intercept missiles fired from up to 1,500 miles away and above the earth’s atmosphere. 

The air defense system known as David’s Sling is also designed to intercept enemy planes, drones, tactical ballistic missiles, medium to long-range rockets and cruise missiles fired at a range of 25 to 190 miles away. 

IDF spokesman Rear Adm. Daniel Hagari said that it was believed the Iranian strikes had stopped, and told Israelis it was safe to leave their shelters.

“During the defense, we carried out quite a few interceptions. There are some impacts in the center and areas in the south of the country,” Hagari said Tuesday night local time. “At this stage we are still carrying out an assessment [of the attack], but we are unaware of casualties.”