A 21-year-old hacker from Kosovo was sentenced to 20 years in a U.S. prison after he was found guilty of aiding the Islamic State group. Ardit Ferizi reportedly passed on personal data of more than 1,000 American military and government personnel to the terrorist organization also known as ISIS.

Ferizi pleaded guilty to charges of providing material support to the terrorist group, which has captured large swathes of areas in Iraq and Syria, and has conducted several attacks on U.S. soil. Ferizi was arrested in Malaysia in October 2015 and extradited to the U.S. in January this year, BBC reported.

At a court hearing in Virginia, Ferizi, who was known online as Th3Dir3ctorY, was given the maximum possible sentence for his crime. He obtained names, email addresses, passwords, locations and phone numbers for about 1,350 military personnel and federal staff after hacking into several servers of U.S. government offices and corporate computers. According to court documents, Ferizi handed the list to ISIS with the knowledge that the data could help the terrorist group attack the individuals named in it.

U.S. Assistant Attorney General John Carlin spoke after the verdict, calling the case a very real and dangerous threat to U.S. national security.

In a statement in June, the U.S. Department of Justice said the case was the first of its kind and represented “the nexus of the terror and cyber-threats.”

U.S. Attorney Dana J. Boente of the Eastern District of Virginia also said at the time: “Cyber terrorism has become an increasingly prevalent and serious threat here in America, both to individuals and businesses. However, cyber terrorist are no different from other terrorists: No matter where they hide, we will track them down and seek to bring them to the United States to face justice.”