Washington - A tech-savvy US teen pleaded guilty on Thursday to using social media to aid the Islamic State group (ISIS), a crime punishable by up to 15 years in prison, the Justice Department said.Ali Shukri Amin, 17, a resident of Virginia, admitted to providing advice and encouragement to ISIS and its supporters, US prosecutors said.Under the Twitter handle @Amreekiwitness, the youth provided ISIS supporters instruction on using the virtual currency Bitcoin to conceal financial donations to the radical Islamist group.The teenager also offered guidance to ISIS supporters seeking to travel to Syria to fight with the radical Islamist group."Around the nation, we are seeing ISIS use social media to reach out from the other side of the world," said John Carlin, US Assistant Attorney for National Security, using the acronym most frequently employed by Washington officials when referring to ISIS."Their messages are reaching America in an attempt to radicalise, recruit and incite our youth and others to support ISILS's violent causes," he said.The Justice Department said Amin also facilitated travel for another young ISIS recruit, Reza Niknejad, 18, who travelled to Syria to join the group in January.Niknejad was charged on Wednesday in federal court in Virginia with conspiring to provide material support to terrorists, conspiring to provide material support to ISIS and conspiring to kill and injure people abroad.Carlin, in a statement, issued a warning to parents to closely monitor their kids' online interactions."This case serves as a wake-up call that ISIS's propaganda and recruitment materials are in your communities and being viewed by your youth," the federal prosecutor said."This challenge requires parental and community awareness and action to confront and deter this threat wherever it surfaces," he said.