The United States is on high alert for possible attacks by Iranian sleeper cells operating inside the country. The warning comes after U.S. airstrikes on Iranian nuclear facilities in June 2025, which Iran has threatened to answer with retaliation on American soil.
The Department of Homeland Security issued a terrorism alert warning of a “heightened threat environment” lasting through at least September 2025. Officials worry that Iranian operatives already living in the U.S. could be activated to carry out attacks.
What Are Sleeper Cells?
Sleeper cells are secret agents who live quietly in a country for years, blending into normal society. They remain inactive until ordered to conduct espionage, sabotage, or terrorist attacks. Iran uses its Revolutionary Guard Corps and proxy groups like Hezbollah to maintain such cells in other countries.
These operatives are hard to detect because they appear to be ordinary residents going about their daily lives.
Rising Border Crossings
U.S. Customs and Border Protection Commissioner Rodney Scott said the sleeper cell threat “has never been higher.” Thousands of Iranian nationals have entered the U.S. illegally, with many more possibly undetected.
Border Patrol data shows Iranian apprehensions at the southern border jumped from 48 in 2021 to 797 in 2024. Over 1,500 Iranians entered during the Biden administration, with many released after minimal background checks.
More than 150 people on U.S. terror watchlists were stopped at the southern border in the first half of 2025 alone, setting a record.
Recent Escalation
In June 2025, the U.S. bombed key Iranian nuclear sites including Fordow, Natanz, and Isfahan. Iran responded by firing missiles at U.S. bases in the Middle East and warning that sleeper cells inside America could be activated.
Former President Trump reportedly left the G7 summit early due to intelligence warnings about possible sleeper cell retaliation, showing how seriously officials take the threat.
Government Response
The FBI and Homeland Security are closely watching suspected Iranian-linked agents. They are increasing surveillance and asking citizens to report suspicious activity near airports, government buildings, and places of worship.
Officials say there is no need for public panic but urge people to stay alert. The full extent of Iranian infiltration remains unknown, as intelligence agencies cannot definitively assess the scale of the threat.
