The US Customs and Border Protection (CBP) said on Monday that the risk of sleeper cells in the US has "never been higher,” following the US strike on three nuclear sites in Iran.
The US Air Force deployed B-2 stealth bombers armed with GBU-57F/B Massive Ordnance Penetrator bombs against Iran’s nuclear facilities on Sunday morning in an operation named “Midnight Hammer.”
Tension between the regions has risen in the wake of the attack.
"Though we have not received any specific credible threats to share with you all currently, the threat of sleeper cells or sympathisers acting on their own, or at the behest of Iran has never been higher," CBP Commissioner Rodney Scott is reported to have said in an internal memo. The memo warned CBP personnel to stay “vigilant.”
Several US outlets reported that Iran sent a message to US president Donald Trump threatening to activate sleeper cells in the US if an attack went forward. However, the White House has not confirmed whether this is true.
Iran is yet to confirm how much damage was done in the US attacks but has warned that there will be “everlasting consequences” for the action. Iran's President Masoud Pezeshkian said that the US “must receive a response for their aggression.”
What is a sleeper cell?
A sleeper cell is a term used to describe a clandestine terrorist network with members who work undercover in a region until they are ordered to act.
The concept gained more attention during 9/11, but the phenomenon is believed to have existed prior to this. During the Cold War, sleeper cell spies were reportedly deployed by both the Soviet Union and the United States.
Should Americans be worried?
A bulletin from the National Terrorism Advisory System has warned of a "heightened threat environment in the United States," following the US attack on Iran's nuclear sites.
The National Counterterrorism Center had warned in 2018 that an Iran-sponsored or Shia-inspired terror attack in the US was unlikely, unless the US attacked Iran. “Potential triggering events for such Shia HVE violence include US military action against Iran,” the report said.
But whether there are sleeper cells in the US is not publicly known.
In February, Trump’s national security memo reportedly said that Iran instructed proxy groups, including Hezbollah and Islamic Jihad, to insert sleeper cells in the US. Then, on June 12, Israel launched Operation Rising Lion, an aerial attack on Iran. The FBI has been surveilling potential sleeper agents associated with Hezbollah since then, according to CBS News.
Days before the US attack, Iran reportedly sent a message to Trump threatening to green-light the terror sleeper cells, according to NBC News.
However, according to Newsweek, there is no public evidence that Iran has sleeper cells ready to commit terrorist attacks in the US.
Still, the risk of retaliation in some form is possible, putting US public infrastructure and the private sector at risk.
A recent Department of Homeland Security bulletin said: "Iranian government-affiliated cyber actors will probably prioritise retaliatory attacks against Israeli targets in the short term but may target US networks due to their perception of US support for Israeli strikes."
The bulletin warned US critical infrastructure entities to "immediately" assess their security measures. US water and wastewater systems have already been infiltrated, according to the non-profit think tank Center for Internet Security.
