Bomb threats have forced the evacuations of Jewish Community Centers in five states in the US and two schools in Britain, American media reports.
JCCs in cities in Florida, South Carolina, Maryland, Tennessee and Delaware were cleared out after a series of threats were made.
In London, police are investigating claims that explosives were placed next to two schools.
It was not immediately clear if there was a link between the threats.
All clears have been given for JCCs in Miami and Jacksonvile, Florida, as well as in London.
US and British law enforcement are investigating the threats, according to the reports.