Shafaq News/ Israel is on high alert as U.S. officials warn of a potential direct attack by Iran, anticipated to occur within hours.

The threat stems from Iran's vow to retaliate for the killing of Iranian military officers, including Brig-Gen Mohammad Reza Zahedi, a leader in the Quds Force of the Islamic Revolutionary Guard Corps (IRGC), along with his deputy and 11 others in a strike on the Iranian embassy in Syria's capital.

According to sources speaking to CBS News, U.S. officials expect a significant Iranian assault on Israel, potentially involving over 100 drones and numerous missiles targeting military installations across the country.

Notably, Tehran has not disclosed details regarding its response strategy, leaving uncertainty about the extent of its planned actions.

The U.S. State Department issued a travel advisory on Thursday, urging Americans in Israel to remain within major cities, where defense systems like the Iron Dome provide greater protection against incoming attacks. Additional restrictions on travel for U.S. government personnel in Israel are anticipated.

Prime Minister Benjamin Netanyahu emphasized Israel's readiness to respond forcefully, stating, "Whoever harms us, we will harm them," during a visit to Israel Defense Forces personnel at an airbase.

On Thursday, Reuters quoted Iranian sources saying that Tehran indicated to Washington that it intends to respond to Israel's attack on its Syrian embassy in a manner aimed at averting significant escalation, opting for a measured approach rather than acting hastily.

Iranian Foreign Minister Hossein Amirabdollahian delivered the communication from Iran to Washington during a visit on Sunday to the Gulf Arab state of Oman, a frequent intermediary between Tehran and Washington, the sources said.

Iran did not comment on Reuters news.

White House press secretary Karine Jean-Pierre said that the Biden administration had "communicated to Iran that the U.S. had no involvement in the strike" in Syria.

"We warned Iran not to use this attack as a pretext to escalate further in the region or attack U.S. facilities or personnel," Jean-Pierre said.

On Wednesday, Iranian Supreme Leader Ayatollah Ali Khamenei renewed his threat to punish Israel for attacking the Iranian consulate compound in Syria.

Speaking at the Eid al-Fitr occasion, the Iranian top leader said, "The evil regime made a mistake and must be punished, and it will be punished."

He stated, "Consulates and embassies are considered sovereign territories of the countries they represent, so when they attacked the consulate, it was tantamount to attacking our own sovereign land."

Iranian President Ebrahim Raisi declared that the" cowardly crime will not go unanswered."

"Having failed to destroy the will of the resistance front, the Zionist regime [Israel] has put blind assassinations back on its agenda to save itself," he said.

Even Iranian proxies in the Middle East warned of the retaliation.

Hezbollah, the Iran-affiliated armed group that has been swapping attacks with Israel across the border with Lebanon since the start of Israel's war on Gaza, joined in, warning that the attack on the Iranian diplomatic premises "will not pass without the enemy receiving punishment and revenge price."

The Secretary-General of Hezbollah, Sayyid Hassan Nasrallah, stated that Israel's attack on Iran's consulate in Damascus signified a "turning point," indicating that an Iranian retaliation was "definitely coming."

"Be certain, be sure, that the Iranian response to the targeting of the consulate in Damascus is coming against Israel," Sayyid Nasrallah said in the televised speech marking Quds (Jerusalem) Day.

The head of Iraq's Popular Mobilization Forces (PMF), Abdul Aziz al-Mohammedawi, known by his nom de guerre "Abu Fadak," said that they are awaiting a decision from Iran's Supreme Leader Ayatollah Ali Khamenei on how to respond to the Israeli airstrike.

"What is happening now between all the resistance groups in Yemen, Iraq, Lebanon, Palestine, and also in the Islamic Republic of Iran is a declaration of the end of Israel," Abu Fadak told media outlets in Iran.

"We are waiting for the decision of the Iranian leader to see what's next and what the response will be to Israel's attack on the Iranian consulate in Damascus and the killing of some of the IRGC's commanders," he added.

Israel has not declared responsibility for the Syria attack. However, Israeli Defence Minister Yoav Gallant struck a defiant tone in comments made, albeit without mentioning Iran.

Israel is in a war on multiple fronts "both offensively and defensively," he told parliament's Defense and Foreign Affairs Committee.

"We operate everywhere, every day, in order to prevent our enemies from gaining strength and in order to make it clear to anyone who acts against us – all over the Middle East – that the price for action against Israel will be a heavy one."