A man from Kosovo accused of hacking into a U.S. company’s server and passing the personal information of American service members to the Islamic State appeared for the first time in a U.S. court Wednesday.

Dressed in a green jail jumpsuit, Ardit Ferizi, 20, said only “yes, sir” during a brief appearance in front of Magistrate Judge Ivan D. Davis in federal district court in Alexandria. The judge appointed the public defender’s office to represent Ferizi, who was led away by U.S. marshals. He is next scheduled to appear in court Friday.

Ferizi was detained last year in Malaysia on a U.S. provisional arrest warrant and extradited several days ago to the United States, authorities said. He is facing several charges, including providing material support to a terrorist organization and aggravated identity theft.

U.S. authorities have accused Ferizi of stealing the American service members’ data, then passing it to Junaid Hussain, a British citizen and Islamic State member.

Hussain in August posted links on Twitter to the names, email addresses, passwords, locations and phone numbers of 1,351 U.S. military and other government personnel. He was killed in a drone strike later that month.