U.S. Customs and Border Protection (CBP) has warned that the threat posed by potential sleeper cells within the United States is at an all-time high, although no specific or credible threats have been identified at this time.
In an internal memo circulated on Saturday and obtained by NewsNation, CBP Commissioner Rodney Scott stated that the agency has recorded “thousands of Iranian nationals” entering the country illegally, with many more likely among those classified as “gotaways”, individuals who evade apprehension at the border and whose identities are unknown to U.S. authorities.
“Though we have not received any specific credible threats to share with you all currently, the threat of sleeper cells or sympathizers acting on their own, or at the behest of Iran, has never been higher,” the memo read.
Commissioner Scott urged CBP personnel to remain “vigilant” in light of the evolving geopolitical landscape, The Hill reports.
What are 'Sleeper Cells'?
"Sleeper cells" are spies or terrorists who can remain inactive for long periods of time until they are ordered to act, often across borders.
The memo follows a significant escalation in regional tensions, as President Donald Trump announced over the weekend that U.S. forces had carried out airstrikes on three Iranian nuclear sites.
The strikes mark a deeper involvement by the United States in the ongoing conflict between Iran and Israel, raising concerns about possible retaliatory measures both abroad and domestically.
As reported by NBC News, sources say Iran sent an official announcement to President Trump in the days before the US carried out strikes on Iran's nuclear sites, threatening to activate sleeper-cell terror inside the United States if it were attacked.
National security experts and intelligence analysts have also raised concerns that Iran may respond to U.S. involvement through non-traditional means, including cyberattacks or leveraging covert networks abroad.
Speaking to NewsNation, investigative correspondent Rich McHugh said: “Experts that we’ve talked to said that should the U.S. join these strikes against Iran, they may try to activate these sleeper cells in the U.S. and the West.”
On Sunday, retired General Frank McKenzie, who previously served as commander of U.S. Central Command (CENTCOM), echoed similar concerns. In an interview, McKenzie said U.S. personnel stationed in the Middle East, particularly in Iraq and Syria, could face an elevated risk of retaliation from Iranian-backed militias or proxy forces.
“Our troops are certainly vulnerable,” McKenzie said, per The Hill. “Iran has a long track record of using regional militias to conduct asymmetric warfare. It’s a key component of how they operate.”
On Monday (June 24), Iran launched a missile strike on a U.S. military installation in Qatar, in what officials described as a response to recent American airstrikes on three of Iran’s nuclear facilities.
The strike targeted Al Udeid Air Base, which hosts U.S. and coalition forces and serves as the headquarters of the Combined Air Operations Center.
Qatar's Ministry of Foreign Affairs confirmed that its air defense systems intercepted the incoming missiles, calling the incident "a flagrant violation of Qatar’s sovereignty, its airspace, and international law," BBC News reports.
According to Iranian state media, the number of missiles fired was equivalent to the number of bombs the U.S. used in its weekend strikes on nuclear sites in Fordow, Natanz, and Esfahan. The Iranian government stated that the attack was a proportional response to what it described as an act of aggression, per The Independent. No casualties have been reported.
U.S. officials have not publicly confirmed the full extent of damage, but CNN reported that Iran issued a warning ahead of the strike, which may have mitigated the impact.
President Donald Trump responded to the development on Truth Social, stating: “Most importantly, they’ve gotten it all out of their ‘system,’ and there will, hopefully, be no further HATE.” He added: “Congratulations world, it's time for peace.”
Iranian President Masoud Pezeshkian also addressed the situation on X, writing: “We neither initiated the war nor [are] seeking it. But we will not leave invasion to the great Iran without answer.”
In recent years, U.S. intelligence officials have expressed concern about Iran’s ability to establish covert influence networks, particularly through individuals who enter the country undetected or through unauthorized means.
While the presence of “sleeper cells” - individuals who remain dormant for extended periods until activated - has long been a theoretical concern, Saturday’s memo represents one of the strongest public acknowledgments of that risk from a senior CBP official.
As of now, federal authorities continue to emphasize that no specific threats to the U.S. homeland have been identified, but operational readiness and intelligence coordination remain a top priority.