“No such threat from Iran to our homeland exists, and it never did,” Leavitt said Thursday.

President Donald Trump was asked about it Wednesday at Joint Base Andrews.

“It’s being investigated, but you have a lot of things happening. All we can do is take ’em as they come,” Trump said.

Special information bulletins from the FBI are fairly common and can cover everything from possible security issues to recommendations for officer awareness around fentanyl that were sent out when the drug began to proliferate the streets, said Jonathan Kohlhepp, an adjunct lecturer at John Jay College of Criminal Justice. Depending on international conflicts, they can be issued monthly or even a few times a month, but urgent information is communicated much differently, he said.

“Generally, bulletins are sent to raise awareness for local law enforcement on something that has hit the FBI’s radar that they feel has enough credibility that they just want to raise that awareness,” said Kohlhepp, who served on the FBI’s Joint Terrorism Taskforce.

If the information required urgent or immediate action, Kohlhepp said the FBI would be more likely to arrange a conference call with the needed partners or make more urgent contact.

Police in Los Angeles and San Francisco said they were monitoring world events for any risks to their cities. Both said they’re working closely with state and federal authorities.

Associated Press reporter Claudia Lauer in Philadelphia contributed to this report.