U.S. intelligence agencies have intercepted encrypted communications likely originating from Iran, prompting a federal alert to law enforcement about a possible activation signal for sleeper cells.

The alert signals analysis of a transmission relayed across multiple countries shortly after the death of Iran's Supreme Leader Ayatollah Ali Khamenei on February 28, 2026. Khamenei was killed during coordinated U.S.-Israeli strikes known as Operation Epic Fury, which also claimed the lives of senior Iranian officials and over 1,200 people, including schoolgirls. Iran retaliated with missile barrages on U.S. bases and facilities in the region, killing seven American service members.

The encoded message appeared intended for recipients with the decryption key and may provide instructions to prepositioned sleeper assets outside Iran, according to the alert. While no specific operational threat or location was identified, authorities urged heightened situational awareness and monitoring of suspicious radio-frequency activity.

FBI Director Kash Patel stated that counterterrorism and intelligence teams are working around the clock to disrupt potential threats on U.S. soil. The bureau has increased surveillance of suspected domestic networks amid fears of retaliation from Iran-backed groups like Hezbollah and Hamas.

Former FBI Assistant Director Chris Swecker warned that the current moment presents a high risk for violent action by such cells. "If ever there's going to be a Hezbollah cell or a Hamas cell act in the United States in a violent way, it's now," Swecker told Fox News. He noted U.S. awareness of existing cells and lone sympathizers, some emerging in protest groups, exacerbated by prior border vulnerabilities.

Recent incidents have heightened concerns. In Austin, Texas, Ndiaga Diagne, a 53-year-old from Senegal, killed two people and injured 14 in a shooting the day after the strikes began. He wore a shirt with an Iranian flag and a hoodie reading "Property of Allah." Separately, two Pennsylvania teens allegedly threw an explosive device at an anti-Islam protest in New York City, with possible ISIS links under investigation.

Texas Governor Greg Abbott emphasized taking Iranian sleeper cell threats seriously, deploying the National Guard, and boosting security after the Austin attack. The NYPD has also stated it is watching for sleeper cells in New York City.

Iran has named Mojtaba Khamenei, son of the former leader, as the new supreme leader amid ongoing regional tensions. Counterterrorism experts like Jason Pack, a retired FBI agent, described routine pre-conflict monitoring but noted the potential for a significant shift in the domestic threat environment.

No imminent plots have been confirmed, but U.S. agencies remain vigilant as the conflict evolves.