Michael Ron David Kadar, 18, who was arrested by Israeli police in March, was charged in Florida and Georgia with making threatening communications, making threats related to explosives and cyberstalking.
The alleged offences date back to August 2015 in connection to threats made against primary schools and homes in Georgia.
The calls he is alleged to have made were extremely menacing, according to the FBI, with one bomb threat claiming that “in a short time, a large number of Jew children are going to have their heads blown off from the schrapnel.”
Kadar, who has dual citizenship and lives in Israel, is said by his American-born mother to be autistic and to have a brain tumour, which she believes could explain his alleged behaviour. She told NBC News she is “shocked and horrified” at the allegations.
“He’s autistic. He can’t control it. He can’t think straight” she said, claiming he was home-schooled after he was unable to function in school due to a brain tumour.
His father, who is Israeli, said: “To all the Jews in America, I want to say clearly, we are very, very sorry, from the bottom of our hearts.“
Both parents were filmed in silhouette to protect their identities. His name had been withheld by Israeli authorities pending a formal indictment.
Kadar’s lawyer has told reporters that while the teenager has a high IQ, he has the emotional intelligence of a five-year-old.
Over the course of two years, Kader is accused of having threatened multiple Jewish community centres and schools in Canada, the US, Australia and New Zealand, as well as airports and specific commercial airlines.
According to the Georgia complaint, the calls forced thousands of children to be evacuated from various schools.
”Today's charges into these violent threats to Jewish community centres and others represent this department's commitment to fighting all forms of violent crime,“ US Attorney General Jeff Sessions said in a statement.
”These threats of violence instilled terror in Jewish and other communities across this country and our investigation into these acts as possible hate crimes continues.“
The FBI said it had issued more than 100 subpoenas and search warrants to various internet providers in order to track down the source of the malicious phone calls.
They allege that Kadar disguised his voice through text-to-voice services or with a spoofing app and used the term “bloodbath” repeatedly in his calls while repeatedly referring to a “bomb”.
The bureau also claims that Kadar repeatedly searched for news reports into the bomb hoaxes, and that they were able to deduce that IP addresses in Israel were connected with the calls.
A joint FBI-Israeli investigation began last Autumn, and also involved authorities in Australia and New Zealand.
Authorities believe that Kadar kept meticulous records of his activities and organised the threats he allegedly made by date and location on a USB drive on his computer.
Threats were made over the two year period to Jewish community centres in states including New York, Alabama, Ohio, Illinois and Texas, although Kadar is charged only in relation to threats made in Florida and Georgia.
Kadar is currently being detained in Israel and faces charges there for the same threats. The Department of Justice said it could not say with certainty whether Kadar will be extradited to the United States to face charges.