The suspect, 20-year-old Ardit Ferizi, is believed to be the leader of a Kosovar Internet hacking group called Kosova Hacker’s Security. He was arrested last month at the request of American authorities and will be extradited to the United States
Ferizi communicated with an Islamic State (IS) member in Syria about hacking servers containing information and details of US security personnel, according to Malaysian police.
"The details were then transferred to the operation unit of the IS group for further action," police said in a statement.
The US Justice Department said Ferizi, a known hacker, had been charged with hacking the personal information of 1,351 US military personnel and federal employees and supporting Islamic State, Reuters reported.
"This case is a first of its kind and, with these charges, we seek to hold Ferizi accountable for his theft of this information and his role in ISIL's targeting of US government employees," Assistant US Attorney General John Carlin said in a statement.
Ferizi allegedly provided the data to Islamic State members including Junaid Hussain, a British hacker who US and European officials said was a top cyber expert for Islamic State in Syria. Hussain was killed in a US drone strike on August 25, a US source told Reuters at that time.
Ferizi entered Malaysia in August 2014 to study computer science in Kuala Lumpur, Malaysian police said.
Between April and August, the complaint says, Ferizi gave the information to Islamic State. On August 11, Hussain in turn posted a tweet titled "NEW: U.S. Military AND Government HACKED by the Islamic State Hacking Division!” which contained a hyperlink to a 30-page document.
The document said in part: "We are in your emails and computer systems, watching and recording your every move. We have your names and addresses."
It said that information would be passed on to Islamic State fighters, "who soon with the permission of Allah will strike at your necks in your own lands!"
The Justice Department said: "This posting was intended to provide ISIL (Islamic State) supporters in the United States and elsewhere with the [information] belonging to the listed government employees for the purpose of encouraging terrorist attacks against those individuals."
Muslim-majority Malaysia has arrested more than 100 people this year for suspected links to Islamic State, including six members of the country’s security forces.