Ali Shukri Amin, 17, pleaded guilty to charges of conspiring to provide material support and resources to IS, according to a Department of Justice statement.
Amin used Twitter to advise and encourage IS and its sympathizers, including tips on how to use bitcoin to conceal sending funds to the group. The American used the Twitter handle @Amreekiwitness, which was set up in June 2014 and grew to have over 4,000 followers. The account has since been suspended.
Amin tweeted a link to an article on his blog that described how bitcoin works, how it could help jihadis and how they could use DarkWallet, an anonymous platform, to send bitcoin, according to a statement of facts filed with a plea agreement in the U.S. District Court for the Eastern District of Virginia, Alexandria Division.
He also admitted facilitating the travel of another teenager, 18-year-old Reza Niknejad, to Syria to join IS. Amin faces a maximum penalty of 15 years in prison if convicted.
Assistant Attorney General for National Security John Carlin described the case as a "wake-up call" that IS recruiting efforts are reaching U.S. youth, and warned that social media is giving the group global reach.
Articles on bitcoin by an Ali Amin, including one entitled "Why we need to fund Dark Wallet," have appeared on the digital currency news site Coinbrief. The site did not immediately respond to a request for information.
Amin's guilty plea follows a report by the SITE Intelligence Group about an online post seeking bitcoin donations for IS. SITE director Rita Katz described in a 2014 Time online column how the U.S. Department of State's @ThinkAgain_DOS Twitter account once sparred about IS with @Amreekiwitness.
Various news reports over the past two years have also speculated on whether IS militants are actually using or benefitting from bitcoin. U.S. officials have long cautioned that virtual currencies, while offering benefits to the financial system, can also be exploited by criminals and terrorists.
Tim Hornyak covers Japan and emerging technologies for The IDG News Service. Follow Tim on Twitter at @robotopia.