Emergency services work at a destroyed building hit by an air strike in Damascus, Syria, Monday, April 1, 2024. An Israeli airstrike has destroyed the consular section of Iran's embassy in Damascus, killing or wounding everyone inside, Syrian state media said Monday.
Washington CNN  — 

The US is on high alert and actively preparing for a “significant” attack that could come as soon as within the next week by Iran targeting Israeli or American assets in the region?in response to Monday’s Israeli strike in Damascus?that killed top Iranian commanders, a senior administration official tells CNN.

Senior US officials currently believe that an attack by Iran is “inevitable” – a view shared by their Israeli counterparts, that official said. The two governments are furiously working to get in position ahead of what is to come, as they anticipate that Iran’s attack could unfold in a number of different ways – and that both US and Israeli assets and personnel are at risk of being targeted.

A forthcoming Iranian attack was a major topic of discussion on President Joe Biden’s phone call with Israeli Prime Minister Benjamin Netanyahu on Thursday.

As of Friday, the two governments did not know when or how Iran planned to strike back, the official said.

A direct strike on Israel by Iran is one of the worst-case scenarios that the Biden administration is bracing for, as it would guarantee rapid escalation of an already tumultuous situation in the Middle East. Such a strike could lead to the Israel-Hamas war broadening into a wider, regional conflict – something Biden has long sought to avoid.

It has been two months since Iranian proxies attacked US forces in Iraq and Syria, a period of relative stability after months of drone, rocket and missile launches targeting US facilities. The lone exception came on Tuesday, when US forces shot down a drone near al-Tanf garrison in Syria. The drone attack, which the Defense Department said was carried out by Iranian proxies, came after the Israeli strike on the Iranian embassy in Damascus.

“We asses that al-Tanf was not the target of the drone,” a defense?official said?Tuesday. “Since we were unable to immediately determine the target and out of safety for US and coalition partners, the drone was shot down.”

The incident came after the Israeli airstrike on the Iranian embassy in Damascus on Monday, though an Israel Defense Forces spokesman told CNN that their intelligence showed the building was not a consulate and is instead “a military building of Quds forces disguised as a civilian building.”

Israel has carried out numerous strikes on Iran-backed targets in Syria, often targeting weapons shipments intended for Hezbollah, a powerful Iranian proxy in Lebanon. But the targeting of the embassy itself marks a significant escalation, since embassies are considered the sovereign territory of the nations they represent.

Iran vowed to take revenge?after Israel’s airstrike on Iran’s embassy complex in Syria, which killed at least seven officials. Mohammed Reza Zahedi, a top commander in Iran’s elite Revolutionary Guards (IRGC),?and senior commander Mohammad Hadi Haji Rahimi were among those killed,?according to Iran’s Foreign Ministry.

At least six Syrian citizens were also killed, Iranian state television reported on Tuesday.

Zahedi, a former commander of the IRGC’s ground forces, air force, and the deputy commander of its operations, is the most high-profile Iranian target killed since then-US President Donald Trump ordered the assassination of IRGC Gen. Qassem Soleimani in Baghdad in 2020.

The US was quick to inform Iran that the Biden administration was not involved and had no advance knowledge of Monday’s strike on the embassy and has warned Iran against coming after American assets.

“The United States had no involvement in the strike and we did not know about it ahead of time,” a National Security Council spokesperson told CNN earlier this week.

The US has warned Iran not to use the Israeli strike in Damascus as “a pretext to attack US personnel and facilities,” a State Department spokesperson told CNN Friday.

The warning was sent in response to a message from Iran, the spokesperson said. Iran’s message to the US blamed the US for the Damascus attack, a senior administration official said, though it was not clear what, if anything else, Iran conveyed to the US in that initial message.

The deputy chief of staff of the Iranian president, Mohammad Jamshidi, said on X Friday that “in a written message, the Islamic Republic of Iran warns US leadership not to get dragged in Netanyahu’s trap for US: Stay away so you won’t get hurt.” He added that in response, the US asked Iran not to target American facilities.

“As Iran noted publicly, we received a message from them,” the State Department spokesperson told CNN when asked about Jamshidi’s post. “We responded by warning Iran not to use this as a pretext to attack US personnel and facilities. We did not ‘ask.’”

A senior administration official described the US’ warning to Iran as: “Don’t think about coming after us.”

The State Department spokesperson did not provide further information about how the US’ message was conveyed to Iran.

The United States considers its own embassies and consulates abroad, as well as foreign countries’ embassies and consulates in the US, to have a special status.?According to the US State Department, “an attack on an embassy is considered an attack on the country it represents.”

On Tuesday, the Pentagon’s Deputy Press Secretary Sabrina Singh said the US’ assessment was that Israel had carried out the airstrike.

“That’s our assessment, and it’s also our assessment that there were a handful of IRGC top leaders there. I can’t confirm those identities, but that’s our initial assessment right now,” Singh said.

Israel has intensified its military campaign against Iran and its regional proxies?following the October 7 attack on Israel by Tehran-backed Palestinian group Hamas, which killed about 1,200 people and saw more than 200 taken hostage.

Israel’s subsequent war in Gaza has killed more than 32,800 people, according to the Ministry of Health in the besieged enclave, wrought widespread destruction and brought more than 1 million people to the brink of a man-made famine.

This story has been updated with additional reporting.

CNN’s Oren Liebermann, Helen Regan,?Hamdi Alkhshali, Tamara Qiblawi and Natalie Barr contributed to this report.