President Donald Trump claiming that the bombings of Iran's nuclear sites "completely and totally obliterated" the sites. However, reports suggesting Iran may have evacuated critical nuclear assets beforehand, combined with heightened rhetoric from Iranian leaders, have fuelled speculation about potential retaliation. Among the concerns raised on platforms like YouTube and X is the possibility of Iranian-backed sleeper cells conducting urban terrorism in the United States, with claims that such cells infiltrated the country during the Biden administration's tenure (2021–2025) due to lax border policies.
Sleeper cells are covert operatives who integrate into a target society, living unassuming lives until activated to carry out attacks or espionage. Iran, through its Islamic Revolutionary Guard Corps (IRGC) and Ministry of Intelligence (MOIS), has a history of supporting such networks, primarily via proxies like Hezbollah, a US-designated terrorist organisation. Concerns about Iranian sleeper cells in the US gained traction after the 2020 assassination of IRGC Quds Force commander Qasem Soleimani, ordered by then-President Trump. Since then, the FBI and Department of Homeland Security (DHS) have intensified surveillance of potential Iran-backed operatives, citing plots against US officials, including John Bolton and Trump himself.
Historically, Iran has not conducted large-scale terrorist attacks on US soil, though it has targeted critics abroad, such as the 1994 Buenos Aires Jewish Community Center bombing attributed to Hezbollah. The IRGC and MOIS have relied on asymmetric warfare, including proxy attacks and assassinations, to maintain plausible deniability. For instance, in 2022, the US Justice Department charged an IRGC operative with plotting to assassinate Bolton, indicating Iran's intent to target high-profile figures. While these plots suggest capability, no major Iranian-backed terrorist attack has materialised in the US, raising questions about the scale and immediacy of the threat.
The narrative that Iranian sleeper cells infiltrated the US during the Biden administration stems from concerns over border security. Former White House Border Czar Tom Homan reported that 1,272 Iranian nationals were among over 10 million illegal border crossers between 2021 and 2024, with some encounters involving individuals from Iran, Syria, and Turkey, alongside items like prayer mats. National security experts, including former FBI officials and Michael Balboni, former New York Homeland Security advisor, have warned that lax border policies may have allowed terrorists to enter undetected. Posts on X from figures like Laura Loomer and Charlie Kirk amplify these concerns, claiming "millions of jihadi sleeper cells" entered due to "open borders."
Several factors influence the likelihood of Iranian-backed sleeper cells conducting urban terrorism in the US following the June 2025 strikes:
1. Iran's Strategic Calculus and Retaliatory Capacity
Iran's leadership, including Supreme Leader Ayatollah Khamenei, has vowed retaliation, describing the US strikes as a "very big red line." However, Iran's weakened state, following Israel's Operation Rising Lion and the US strikes, may limit its ability to orchestrate complex attacks. The strikes damaged Iran's nuclear infrastructure, air defences, and missile stockpiles, and Hezbollah's reluctance to escalate suggests constrained proxy capabilities.
Urban terrorism, such as bombings or shootings in cities like New York or Washington, DC, requires significant planning, resources, and local networks. Experts like Barak Seener argue that a "volatile" Iran, facing regime survival threats, might resort to desperate measures, including activating sleeper cells. Yet, Iran's historical preference for targeted assassinations over mass-casualty attacks suggests a lower likelihood of indiscriminate urban terrorism. Past plots, like those against Bolton and Masih Alinejad, focused on high-profile individuals rather than public spaces. Moreover, Iran's reliance on Hezbollah, which has been weakened by Israeli operations, may limit its operational reach.
The FBI, under Director Kash Patel, has intensified surveillance of Hezbollah-linked operatives since Israel's strikes began on June 13, 2025. The DHS issued a National Terrorism Advisory System bulletin on June 23, warning of a "heightened threat environment" post-strikes. The Justice Department's success in thwarting a 2024 plot to assassinate Trump demonstrates robust counterterrorism capabilities. The FBI's Joint Terrorism Task Forces and focus on Iranian-linked charities, religious centres, and schools further mitigate risks.
However, identifying sleeper cells is challenging. Operatives often blend into communities, as seen in the case of Ali Kourani, a Hezbollah agent sentenced in 2019 for spying on US facilities. The decentralised nature of potential cells, especially if IRGC command structures are disrupted, could lead to "lone wolf" actors, harder to detect but less capable of coordinated attacks. Enhanced border security under the Trump administration, including zero illegal immigrant releases in May 2025, reduces the risk of new operatives entering.
Iran's retaliatory options are constrained by its weakened military and economic isolation. Blocking the Strait of Hormuz or attacking US bases in the region are more likely than domestic US attacks, given logistical challenges. Domestically, Iran may exploit anti-American sentiment to rally support, but orchestrating urban terrorism risks severe US retaliation, as Trump warned: "If they do it, they get obliterated." Iran's leadership, focused on regime survival, may avoid actions that provoke a full-scale US response.
The likelihood of Iranian-backed urban terrorism in the US is low to moderate but not negligible. Several factors support this assessment:
Low Probability of Large-Scale Attacks: Iran's history suggests a preference for targeted assassinations over mass-casualty urban attacks. The logistical complexity of coordinating bombings or shootings in US cities, combined with weakened proxy networks, reduces the feasibility of such operations. No confirmed Iranian terrorist attack has occurred on US soil, and recent plots have been disrupted.
Moderate Risk of Smaller-Scale Plots: The presence of Iranian or Hezbollah operatives, potentially infiltrated during 2021–2024, poses a risk of smaller, targeted attacks, such as assassinations or low-yield bombings. The 1,272 Iranian nationals crossing the border and past plots against US officials indicate intent, but not widespread capability.
Mitigating Factors: Robust US counterterrorism measures, including FBI surveillance and DHS alerts, limit Iran's ability to activate cells undetected. Enhanced border security and weakened Iranian proxies further constrain the threat.
If Iran were to activate sleeper cells, several scenarios are possible:
1.Targeted Assassinations: Iran could target former officials like Bolton or critics like Alinejad, consistent with past behaviour. Such attacks would aim to send a message without provoking a massive US response.
2.Low-Yield Terrorist Acts: Small-scale attacks, such as bombings in public spaces or attacks on infrastructure, could occur but are less likely due to Iran's limited US networks and FBI monitoring.
3.Proxy Escalation: Iran may rely on Hezbollah or other proxies in Latin America or Europe to strike US interests abroad, as seen in the 1994 Buenos Aires attack, rather than risk direct attacks on US soil.
While the threat of Iranian sleeper cell urban terrorism in the US following the June 2025 strikes exists, its likelihood is low to moderate due to Iran's strategic constraints, weakened proxies, and robust US counterterrorism efforts. Claims of widespread infiltration during the Biden administration are exaggerated, with limited evidence supporting large-scale sleeper cell networks. However, the risk of targeted attacks remains, necessitating continued vigilance. The FBI and DHS's proactive measures, combined with Iran's focus on regime survival, suggest that urban terrorism is not the most probable form of retaliation. Instead, Iran may opt for regional proxy attacks or cyber operations. Worry enough.