Federal authorities say a Pennsylvania teenager already accused of trying to assist the Islamic State group also tweeted out the names and addresses of military personnel with threats of violence.

Harrisburg resident Jalil Ibn Ameer Aziz was charged Wednesday in a superseding federal indictment with solicitation to commit a crime of violence and transmitting a communication containing a threat to injure.

Prosecutors allege he tweeted the names, addresses, photographs and military branches of approximately 100 service members with statements such as "kill them in their own lands, behead them in their own homes, stab them to death as they walk their street thinking that they are safe."

Assistant federal public defender Thomas Thornton says the charges involve "a 19-year-old kid tweeting and retweeting" from his bedroom.