Israeli police have arrested a 19-year-old as the primary suspect in a string of bomb threats targeting Jewish community centres and other institutions in the US.
Police spokesman Micky Rosenfeld described the suspect, an Israeli Jewish man, as a hacker, but said his motives were still unclear.
Israeli media identified him as an American-Israeli dual citizen and said he had been found unfit for compulsory service in the Israeli military.
Dozens of anonymous threats had been phoned in to Jewish community centres in the US over the past two months.
The Anti-Defamation League said there have been more than 120 bomb threats against US Jewish community centres and day schools since January 9.
Those threats led to evacuations of the buildings, upset Jewish communities and raised fears of rising anti-Semitism.
The threats were accompanied by acts of vandalism on several Jewish cemeteries.
The threats led to criticism of the White House for not speaking out fast enough. Last month, the White House denounced the threats and rejected “anti-Semitic and hateful threats in the strongest terms”.
Mr Rosenfeld said the suspect allegedly placed dozens of threatening phone calls to public venues, synagogues and community buildings in the US, New Zealand and Australia.
He also placed a threat to Delta Airlines, causing a flight in February 2015 to make an emergency landing.
Mr Rosenfeld said the man, from the south of Israel, allegedly used advanced technologies to mask the origin of his calls and communications to synagogues, community buildings and public venues.
He said police searched his house on Thursday morning and discovered antennae and satellite equipment.
After an intensive investigation in co-operation with FBI representatives who arrived in Israel, as well as other police organisations from various countries, technology was used to track down the suspect who had made the threats around the world, Mr Rosenfeld said.
In Washington, the FBI confirmed the arrest but made no further comment.