Conflict could unleash threats on U.S. soil

Islamic Republic may deploy sleeper cells, lone wolves or cyberattacks, federal authorities warn

- By Richard Winton

SPENCER PLATT Getty Images

SMOKE rises, top, after an Israeli strike on Beirut's southern suburbs. Above, Grand Central Terminal amid the "heightened threat environment" in New York.

With U.S. and Israeli forces continuing offensive strikes on Iran, federal counter-terrorism authorities are warning that the desperate theocracy could launch retaliatory strikes on American soil using sleeper cells, affiliated Iranian terrorist groups, lone wolf sympathizers or targeted cyberattacks.

Within days of the killing of Iranian Supreme Leader Ayatollah Ali Khamenei on Feb. 28, cryptic messages were broadcast globally on a new shortwave radio frequency.

"Tavajjoh! Tavajjoh!" the message began, using the Persian word for "attention." The eerie male voice then read a seemingly random string of numbers.

The monotone transmission recalled the manner in which deep-cover Cold War spies for the KGB and CIA once received orders. Using a special encryption code, the operatives could translate the numerals into a readable message. Although messages from so-called number stations have been broadcast for decades, they are now less prevalent in the digital encryption age.

Federal authorities warned local law enforcement that they had detected a new broadcast of a likely encoded sequence that could be "an operational trigger" for "sleeper assets" potentially on U.S. soil.

At a news conference Monday, President Trump said officials were "on top" of the situation.

"They've been trying for a long time, and we've been very much on top of it," Trump said in response to a question about whether Iran might activate sleeper cells in the U.S. "We're watching every single one of them, yeah. We know a lot about them."