() As the Iranian supreme leader threatens “irreparable harm” if the United States joins Israel’s fight, the White House is warning of so-called Iranian “sleeper cells.” The Trump and Biden administrations have long been concerned about Iran’s ability to direct or inspire attacks within the U.S.

Sleeper cells are spies or terrorists who operate in the U.S. and Western countries and remain inactive until they are essentially ordered to act. Experts who have spoken with said should the U.S. join Israel’s strikes against Iran, they may try to activate these cells.

A recent U.S. Department of Homeland Security threat assessment concurs, saying that the intelligence community expects Iran to remain the primary sponsor of terrorism and continue its efforts to advance plots against individuals, including current and former U.S. officials. That assessment echoed similar guidance from Biden’s Department of Homeland Security in 2024. Experts say given the recent escalation between Israel and Iran, the possibility is very real.

“As the conflict in the Middle East escalates and Iran is being targeted, the regime thinks to itself, ‘Okay, we are on our last throes, and therefore we will go out with a bang, quite literally,’” said Barak Seener, a senior fellow at the Henry Jackson Society. “Its calculus will be very different if its survivability is threatened. Intelligence Services in the U.S. are working overtime to contend and mitigate risks and threats that can emerge on its domestic soil. The more protracted this conflict goes on, the heightened risk for both U.S. forces and assets in the Middle East, but also to U.S. security domestically.”

During last year’s presidential campaign, federal prosecutors charged an operative of Iran’s Islamic Revolutionary Guard and two U.S.-based individuals who were allegedly planning to surveil and assassinate President Trump. That operative reportedly told investigators, Islamic Revolutionary Guard Corps officials encouraged him to plan the attack. In February, Trump’s national security memo claimed Iran has directed its proxy groups, including Hezbollah and Islamic Jihad, to embed sleeper cells in the U.S. to be activated in support of potential terror activity.

“If Israel’s able to decapitate the Islamic Revolutionary Guard Corps command and control, who actually then controls the sleeper cells anymore, do they become more decentralized, more atomized? Do they become more like lone wolf actors? Who pays them because the regime is in its last race? So these are all questions, and for intelligence and security forces, it becomes a lot more challenging to monitor and identify who are going to be imminent threats when they are more decentralized and atomized and functioning like lone wolf actors,” said Seener.

United States Central Command officials tell it is likely that the FBI is currently monitoring potential threats.

Mike Nelson, a retired Special Forces lieutenant colonel with extensive experience CENTCOM, tells that Hezbollah has had sleeper cells in the western hemisphere for some time, including coming through Venezuela. Iranians and Hezbollah used these cells in the past, including the Jewish Community Center bombing in Buenos Aires in 1994, according to Nelson.

“It seems likely (Hezbollah and Iran) would try to activate sleeper cells in the United States as retaliation if the U.S. joins in the strikes, so it would be prudent for the FBI to be monitoring,” Nelson explained.

“The Iranian regime wants this to end with them in power, and their primary concern is survival,” said Nelson. “They do not want the United States to be involved. They most likely will not do anything to provoke (the U.S.) if they think we are going to get involved. Then, one of their options is to attempt asymmetric attacks on the United States. In other words, activating stateside sleeper cells.”

A source close to the White House said the following to :

“POTUS is closely monitoring the situation. POTUS does not want to go to war. The president will avoid war. He does not want to aggravate it. He’s not going to do anything unless he thinks the only way to keep the American people safe is to do something. The genesis of it is to keep the American people safe.”