Iran's threats on U.S. soil: sleeper cells, lone wolves, cyberattacks and eerie numbers code

Federal authorities warn that Iran could launch retaliatory strikes on American soil using sleeper cells, lone wolf sympathizers or cyberattacks.

Did Iran send out Sleeper Cell signal? US alert flags encrypted broadcast after Khamenei's killing in Iran: Report

US authorities intercepted an encrypted transmission believed to originate in Iran that could signal the activation of sleeper cells abroad, according to a federal alert reviewed by ABC News. Here’s what sleeper cells are and why security agencies are concerned.