How real is the threat of Iranian sleeper cells in the U.S.?

Federal officials are warning law enforcement agencies to remain alert after an encrypted broadcast tied to Iran’s regime raised concerns about a possible activation signal for covert operatives abroad. 

While authorities say there is no specific or imminent threat, the alert has revived a long-standing question in U.S. national security circles: how real is the risk that Iran could activate sleeper cells inside the United States?

Intelligence agencies say the threat exists, but evidence is limited

U.S. intelligence agencies have warned for years that Iran and its proxies maintain networks capable of carrying out operations overseas.

A Department of Homeland Security assessment previously concluded that Iran remains a major state sponsor of terrorism and continues efforts to build surrogate networks that could target individuals or interests in the United States. 

In fact, security analysts have documented dozens of Iranian-linked plots or operations tied to the United States over the past decade. According to research compiled by the Washington Institute for Near East Policy, Iranian agents or proxies have been connected to at least 27 plots in the United States, including surveillance operations and attempted attacks. 

However, researchers caution that the existence of networks or sympathizers does not necessarily mean large numbers of dormant terror cells are waiting to strike.

Public reporting has found no confirmed evidence of a large-scale Iranian sleeper-cell network currently operating inside the United States, even though intelligence agencies consider the possibility credible. 

Iran’s strategy relies on proxies and covert networks

Security experts say Iran’s approach to asymmetric warfare often relies on a mix of intelligence operatives, criminal intermediaries and proxy groups.

The Islamic Revolutionary Guard Corps’ Quds Force runs covert operations worldwide and includes specialized units tasked with sabotage, assassinations and clandestine attacks abroad. 

These networks often work indirectly through groups such as Hezbollah or through individuals recruited overseas.

Iran has historically used such methods as a way to strike adversaries without triggering a direct military confrontation. Analysts note that terrorism and covert action have long been part of Tehran’s foreign policy toolkit, particularly when confronting stronger military powers. 

Past cases show the threat is not theoretical

Although rare, several incidents demonstrate that Iranian-linked operatives have attempted activities inside the United States.

One of the most notable examples occurred in 2011, when U.S. authorities uncovered a plot tied to Iran’s Revolutionary Guard to assassinate the Saudi ambassador to the United States at a Washington, D.C., restaurant.

Other cases have involved surveillance of infrastructure or dissident groups. Iranian operatives have been caught monitoring U.S. landmarks and gathering information about Iranian dissidents living in America. 

In recent years, federal investigators have also disrupted several Iranian-backed plots targeting critics of Tehran who live in the United States. 

Experts say retaliation risk rises during conflicts

Concerns about sleeper cells typically intensify during periods of military tension.

Following U.S. strikes against Iranian targets, homeland security analysts warned that the risk of retaliation inside the United States could increase as Tehran seeks asymmetric ways to respond. 

Iran has previously threatened to activate sleeper agents if the United States attacked its territory or leadership, according to intelligence reporting cited in counterterrorism analyses. 

Still, experts say Iran must weigh the consequences carefully. A successful attack on U.S. soil could provoke overwhelming retaliation and escalate conflict dramatically.

Vigilance without panic

For now, officials emphasize that warnings about encrypted communications and potential sleeper assets are largely precautionary.

Security analysts say the most likely threats would involve isolated attacks, criminal proxies or self-radicalized individuals inspired by Iran, rather than large coordinated terror operations.