Israeli charged over hoax bomb-threats to US Jewish centres
The Jewish youth, who lives in Israel, used an online calling service to disguise his voice as that of a woman.
Complaints filed in Georgia and Florida federal courts revealed the identity of Michael Ron David Kadar, 18, a dual US-Israeli national, for the first time.
Kadar was arrested in Israel on March 23 and has remained in detention there.
The teenager made at least 245 threatening phone calls between January and early March this year. Many of the calls were directed at Jewish community centres, the Florida indictment says.
Each of the calls were recorded by Kadar, who saved them along with related media coverage at his home in Ashkelon.
According to the Georgia indictment, Kadar also made over 240 hoax calls to schools in Canada and the US between August and December 2015.
The youth's lawyers say that Kadar suffers from a growth in his head that causes behavioural problems.
The US Justice Department did not say whether it would seek his extradition.