What are sleeper cells and why is the US on high alert after bombing Iran nuclear sites?

Now, security agencies including the FBI and Department of Homeland Security have increased surveillance to counter potential threats linked to Iran or its allies, including Hezbollah.

What are sleeper cells?

Sleeper cells are operatives who live quietly in a country, blending into society until they are told to act. These individuals may work normal jobs and avoid drawing attention. When activated, they could carry out attacks, sabotage or espionage.

Former Homeland Security adviser Michael Balboni told Fox News, “The Iranians have shown a good capability in terms of their intelligence apparatus and operatives being able to work clandestinely. They are determined. The question is how many are in the country and the answer is we don’t know.”

According to Fox News, White House border czar Tom Homan revealed that over 1,200 Iranian nationals reportedly entered the US during former President Joe Biden’s time in office, sparking concerns about potential domestic sleeper cells driven by foreign terrorist organisations.

Homan shared this information on “Sunday Morning Futures” with Maria Bartiromo, highlighting the risks associated with foreign nationals flowing into the country. National security experts are worried that these individuals could pose a threat to US security, especially in light of recent tensions with Iran .

However, US officials are especially concerned about cells linked to Hezbollah, a group supported by Iran. The FBI began stepping up monitoring of suspected Hezbollah-linked agents well before the latest strikes.

The current threat

The National Terrorism Advisory System issued a bulletin warning of a “heightened threat environment” after the strikes on Iran’s nuclear sites. While no specific plot has been identified, the advisory said the risk of violence could rise if Iran calls for retaliation inside the US.

Former FBI assistant director Chris Swecker told Fox News that the situation is made more difficult because of gaps in border controls in recent years. “We don’t know where those thousand Iranians are and who knows how many others got across the border,” he said.

He believes that authorities missed an opportunity to gather intelligence by not thoroughly vetting these individuals, saying “we missed the opportunity to gather intel by interviewing them and thoroughly vetting them. We just simply let them go.” Swecker attributes this to “gross negligence on the part of the Biden administration.”

According to CBS News, potential targets of Iranian-backed plots include high-profile critics of the Iranian government, such as John Bolton, former national security adviser, and Masih Alinejad, an Iranian American journalist. Both individuals have been subject to alleged plots to be harmed, with prosecutors charging people with plotting to kill them in recent years.

The increased surveillance started earlier this month, after Israel’s Operation Rising Lion offensive began, according to the report.

This heightened vigilance stems from longstanding concerns about Iranian operatives, particularly after the 2020 assassination of Iranian General Qasem Soleimani, which prompted the FBI and Department of Homeland Security to bolster counter-threat resources.

Since then, several US-based individuals have been charged with plotting to kill Trump and his former national security adviser John Bolton.

Iran, Israel and the US strikes

The airstrikes ordered by Trump targeted the Fordow, Natanz and Isfahan nuclear sites, which are central to Iran’s ability to produce enriched uranium. Israel’s campaign against Iran’s military and nuclear infrastructure began on 13 June. Trump’s decision to join the offensive marks a major escalation in US involvement.

Iran has described the US strikes as “unforgivable” and vowed to respond. Secretary of State Marco Rubio warned Iran that any attack on the US would be “the worst mistake they’ve ever made,” speaking on Fox Business.

Israel’s Prime Minister Benjamin Netanyahu said on Sunday that Israel was “close” to destroying Iran’s nuclear and missile capabilities.

Sleeper cells: past and potential use

Sleeper cells have long been a concern for US security services. After the 9/11 attacks, agencies increased efforts to detect covert groups that could plan violence while appearing to live normal lives. While the 9/11 hijackers were not sleeper agents living in the US long-term, the attack highlighted the dangers of operatives planning in secret.

Iran has previously been linked to attempts to use such cells for attacks or assassinations abroad. Balboni told Fox News that sleeper cells could target individuals or infrastructure and are difficult to track because they “look just like everyone else.”