Iran May Activate Sleeper Cells Abroad, US Intel Warns

The alert cites “preliminary signals analysis” of a transmission likely of Iranian origin that was relayed across multiple countries shortly after the death of Ayatollah Ali Khamenei. Khamenei, Iran’s Supreme Leader, was killed in a joint US-Israeli attack on February 28.

According to the alert, the intercepted transmission appeared to be encoded and destined for “clandestine recipients” who possess the encryption key. This type of message is typically used to provide instructions to covert operatives or sleeper assets without relying on the internet or cellular networks. The coded signal was reportedly transmitted soon after the assassination of the Supreme Leader.

There have been several allegations against the Iranian regime regarding its support for militant networks. Iran has long been accused of backing, funding, and training a range of militant groups across the Middle East through the Islamic Revolutionary Guard Corps (IRGC) Quds Force, often referring to them collectively as part of the “Axis of Resistance.” Groups reportedly supported by Iran include Hezbollah in Lebanon, Hamas and Palestinian Islamic Jihad in Gaza, the Houthis in Yemen, and several Shia militias in Iraq and Syria, as well as the Zainulabdeen Brigade, which is active in South Asia. Many of these groups have been designated as terrorist organizations by several countries.

Officials say the transmissions could potentially be intended to activate or provide instructions to pre-positioned sleeper assets operating outside Iran.

“While the exact contents of these transmissions cannot currently be determined, the sudden appearance of a new station with international rebroadcast characteristics warrants heightened situational awareness,” the alert said. Although it states there is “no operational threat tied to a specific location,” the notice instructs law enforcement agencies to increase monitoring of suspicious radio-frequency activity.

If the contents of the alert are confirmed, they could reinforce concerns previously raised by law enforcement and counterintelligence officials. Experts have warned about the possibility of retaliatory attacks inside the United States amid the ongoing conflict with Iran.

“If ever there’s going to be a Hezbollah cell or a Hamas cell acting in the United States in a violent way, it’s now,” Chris Swecker, a former assistant FBI director, told Fox News soon after the conflict began.

Following US strikes on Iran on February 28, FBI Director Kash Patel wrote on X that he had ordered “counterterrorism and intelligence teams to be on high alert and mobilise all assisting security assets needed,” indicating that security measures in the United States had already been heightened.

US President Donald Trump, when asked about the possibility of Iran launching an attack on the US mainland, said this week: “I guess we think about it all the time. We plan for it. But yeah, we expect some things. Like I said, some people will die. When you go to war, some people will die.”

Leaders of major American cities such as Los Angeles, Miami, and New York have also announced stronger patrols around sensitive locations, including places of worship, cultural centres, and schools.

The intercepted transmission comes amid heightened security concerns as the conflict in West Asia continues to escalate. Officials in Washington have previously warned that Iran or groups aligned with Tehran could attempt retaliation outside the Middle East.