Under the Biden Administration, authorities intercepted approximately 1,500 Iranians at the border, though officials are more concerned about those who might have slipped through undetected. These individuals could pose significant security risks, with officials warning that “sleeper cells” represent a serious threat to national security.

Senator Bill Hagerty (R-Tenn.), a Senate Foreign Relations Committee member and former US ambassador to Japan, expressed his worries, saying, “The number of individuals who managed to bypass our detection is extremely troubling.”

Hagerty noted that nearly half of those apprehended were released into the United States, as reported by Fox News. Of the 1,504 Iranians detained between 2021 and 2024, around 700 were allowed to stay in the country while awaiting court proceedings.

Iran has been consistently identified by the US as a state sponsor of terrorism.

Customs and Border Patrol data, highlighted by the nonpartisan Niskanen Center, showed an increase in Iranian interceptions, reaching 1,650 from 2022 to 2025. Many Iranians traveled through Sao Paulo, Brazil, a known “hub” for passport fraud.

Hagerty’s concerns followed a federal security alert, which warned of Iran potentially mobilizing “prepositioned sleeper assets.” This comes despite significant losses among Iran’s top leaders due to ongoing US and Israeli airstrikes.

The caution raised fears that Iran, which has continued to hammer its Gulf neighbors and whose retaliation has led to the deaths of at least 13 American service members, could find a way to strike on the home front.

President Trump acknowledged the concerns March 11.

“A lot of people came in through Biden with his stupid open border, but we know where most of them are: We’ve got our eye on all of them, I think,” he said.

Homeland security concerns rose even higher when a deranged Lebanese American man slammed a car packed with explosives into a synagogue in West Bloomfield, Michigan, and an ISIS-linked gunman opened fire at Old Dominion University in Virginia, killing an ROTC instructor.

FBI Director Kash Patel and CIA Director John Ratcliffe also met with Republican senators in the Capitol this month to discuss expiring federal surveillance authority, as security fears at home intensify.

“We don’t know where they are,” Hagerty said. “Put it this way: there’s a greater than 0% probability that there’s a sleeper cell in America today, basically.”

Senate Intelligence Committee vice chair Sen. Ron Wyden (D-Oregon), who is barred from disclosing classified briefings he gets from the administration, also sounded the alarm.

“Let me just tell you, I think that this is a moment with a lot of safety challenges and I’ll leave it at that,” he said.

“There’s good reason to be vigilant,” said Sen. James Risch (R-Idaho), another intelligence panel member.

“I don’t think there’s any question they’re here,” said Sen. Rick Scott (R-Fla.), a Homeland Security member. “We’ve got to be so vigilant … it just takes one person.”