Michael Ron David Kadar leaves court in Rishon Lezion, Israel, on March 23.Federal officials on Friday filed charges against an 18-year-old Israeli American&nbsp;in connection with hundreds of hoax bomb threats this year&nbsp;that had put U.S. Jewish institutions on edge.A criminal complaint filed in federal court in Orlando, Fla.,&nbsp;said Michael Ron David Kadar was behind at least 245 "threatening telephone calls involving bomb threats and active shooter threats" from Jan. 4 to March 7.In another complaint filed in federal court in Macon, Ga.,&nbsp;Kadar was also charged with a series of calls to public schools and residences that either threatened attacks or made false reports about attacks to trick police into showing up, an illegal prank&nbsp;known as "swatting." The calls began in 2015 and continued through this year.He used Google Voice and other digital phone services as well as computerized voice manipulation to disguise his identity, according to the complaints.The arrest was part of a joint operation between the FBI, Israel law enforcement, and police from Australia, New Zealand and Europe. Kadar, who is a dual citizen, was arrested March 23 in Israel, where he lived in the southern city of Ashkelon.&ldquo;Today&rsquo;s charges into these violent threats to Jewish Community Centers and others represent this Department&rsquo;s commitment to fighting all forms of violent crime,&rdquo; Atty. Gen Jeff Sessions said in a statement. &ldquo;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.&rdquo;Kadar isn't the first person charged with making bomb threats against Jewish centers.On March 3, Juan Thompson was arrested in St. Louis on suspicion of&nbsp;making threats to seven Jewish community centers and the Anti-Defamation League&rsquo;s New York headquarters. Police said Thompson, a former journalist with the Intercept, was a copycat who made the threats in an attempt&nbsp;to frame an ex-girlfriend.