The United States is ramping up efforts to protect Americans worldwide, as President Donald Trump mulls wading into Israel’s conflict with Iran.

The actions come as Iran’s Islamist leader warned of “irreparable damage” if Washington joins the escalating volley of airstrikes aimed at destroying Iran’s nuclear ambitions.

The U.S. Embassy in Israel has begun evacuating Americans who want to leave the country, while U.S. diplomats in the Middle East and elsewhere have stepped up security protocols. The Pentagon has also sent warships, fighter jets and other military assets to protect U.S. troops in the region.

“Everything you’re seeing is a signal of how seriously the Trump administration is taking the threat,” said Dana Stroul, a former top Pentagon official in the Biden administration. “It’s an indicator that they think this could get more risky and serious in the coming days and weeks.”

Iran’s Supreme Leader Ayatollah Khamenei on Wednesday warned the U.S. against muscling into the latest conflict, which began last week when Israel struck Iranian nuclear facilities and killed several high-ranking officials tied to its military. Khamenei also said Iran would never surrender — an apparent response to Trump’s social media demand of “UNCONDITIONAL SURRENDER!”

“Any U.S. military intervention will undoubtedly be accompanied by irreparable damage,” Khamenei said, according to media reports from the region.

Despite planned nuclear negotiations between the U.S. and Iran last weekend, Israel carried out the strikes because officials doubted a deal would be struck. Now, Trump is weighing whether to give Israel the bombs it needs to destroy Iranian nuclear facilities that are buried deep underground.

When asked by reporters at the White House on Wednesday about Khamenei’s refusal to give up, Trump seemed unfazed, responding with a “good luck.”

Trump refused to tell reporters later Wednesday afternoon whether he had made a final decision about entering the war — leaving Americans in the Middle East in a continued state of anxiety about the potential for Iranian reprisal.

As the possibility of an Israeli strike on Iran has grown, some U.S. embassies in the region have pulled staff members. Security protocols have also become unusually strict at these diplomatic facilities, with staff headcounts required every day, said a U.S. official in the region. This person, like the others mentioned in this story, was granted anonymity because they were not authorized to publicly talk about the issue.

“I haven’t seen this level of daily internal accountability exercises in years,” the official added.

U.S. Ambassador to Israel Mike Huckabee on Wednesday announced that the embassy would help Americans who wish to leave.

“Urgent notice! American citizens wanting to leave Israel – US Embassy in Israel@usembassyjlm is working on evacuation flights & cruise ship departures,” the ambassador wrote on social media.

U.S. embassies beyond the Middle East are watching the situation and adjusting as needed.

Many have held meetings of their “emergency action committees” — groups that consider whether there needs to be restrictions on activities like diplomats’ travel — as a precaution, a U.S. diplomat in Europe said.

Iran is not as strong a player as it once was in the Middle East. Its proxy militias — especially Hamas in Gaza and Hezbollah in Lebanon — have been severely diminished by Israel since the Hamas attacks on Oct. 7, 2023. Even before the fresh round of Israeli strikes began last week, Israel had exchanged fire with Iran on multiple occasions since late 2023, taking out some key Iranian installations.

Still, Iran maintains some military might. It has already fired drones and missiles — including ballistic missiles — at Israel, and it has multiple options to retaliate against the U.S. should it choose, in particular against U.S. military forces in the Middle East.

There are around 2,500 U.S. troops in Iraq, and several hundred remaining in Syria.

The Pentagon has ordered the USS Nimitz aircraft carrier to leave the Pacific and head to the Middle East, joining a U.S. carrier already there. A third carrier is slated to deploy to Europe by the end of June from its base in Virginia, and could be in the Mediterranean close to Israel if needed, one defense official said.

Two more destroyers capable of providing air defense have also been dispatched to the Israeli coast, along with new F-22, F-16, and F-35 fighter planes and dozens of aerial refueling aircraft. The planes can help track incoming missiles and shoot down missiles and drones.

A former Western intelligence official and a former senior U.S. intelligence official said the spy community suspects Iran has agents it can activate in other countries, including the U.S. Those cells could carry out terrorist attacks or targeted assassinations.

The U.S. intelligence community has for years assessed that Iran’s Islamic Revolutionary Guard Corps — a military branch that reports directly to the supreme leader — is determined to kill Trump or other senior U.S. national security aides in retaliation for a 2020 U.S. drone strike that killed Iranian general Qassem Soleimani. IRGC operatives have tried to enlist criminal gangs inside the U.S. to help carry out some of its plots, according to the U.S. Justice Department.

POLITICO reached out to 11 officials known to have faced assassination threats from Iran. Three did not reply to requests for comment and the others declined to comment on the record due to concerns for their safety. Some potentially face greater danger because Trump pulled their government security details after his reelection.

Four of the officials said that while they have not yet seen evidence of an escalated threat environment, they expect Iran would consider targeted assassinations if the U.S. engaged in fighting against Tehran.

A second former senior U.S. intelligence official questioned whether Tehran intends to attack U.S. interests at this stage, given the likelihood that Trump would hit back. But if Iran’s leaders perceived there to be an existential threat to the future of the regime, they could decide to act, the former official said.

“We know they have the capability to carry out asymmetric attacks globally,” said the former official, who noted that institutions and organizations that represent American soft power could also be targeted, in addition to U.S. and Israeli embassies.

Still, not everyone is convinced by Iran’s chest puffing. One of the former senior U.S. officials argued that Tehran had been built up as “10 feet tall and bulletproof” — but “that was never really consistent with the facts.”

Iran could target the oil infrastructure of America’s Gulf Arab allies with cyberattacks or drone strikes. It could further seek to disrupt nearby shipping lanes critical to global commerce.

Tehran could also detain Americans as leverage if the crisis expands, as it has in the past. Despite repeated U.S. government warnings to Americans not to travel to Iran, many still do. Among them are many Iranian-Americans who have relatives or other reasons to visit.

While the Middle East has long been a tinderbox, former U.S. officials note that parties bent on revenge don’t always carry it out immediately. It could be years before the true fallout of the Israel-Iran war is felt.

“We’ve seen this time and time again — Hezbollah launching terrorist attacks on tourists in Bulgaria years after the killing of top Hezbollah officials or Iran going after American officials years after the killing of Soleimani,” said Ilan Goldenberg, a former national security official during the Biden administration. “It’s totally possible and very likely that we’re able to stop these kinds of things, but you never know. It takes a lot of resources. It takes a lot of time.”

Amy Mackinnon and Paul McLeary contributed to this report.