Former National Guardsman Mohamed Jalloh (26) of Sterling, Virginia has been charged for plotting to help ISIS.
Jalloh attempted to purchase an assault rifle in Chantilly but was not so successful.
According to the Washington Post, he had previously tried to purchase a weapon at the Blue Ridge Arsenal gun store on Friday but was denied for a lack of identification forms. After turning him away, the FBI was in compliance with the store, making sure any gun sold to Jalloh in the future would be inoperable.
Jalloh returned to the gun store on Saturday to buy an assault weapon for $1,200. He was then taken into custody on Sunday.
In federal court in Alexandria this Tuesday court documents revealed a three-month sting and Jalloh's past interactions with ISIS. Authorities say the sting operation began after Jalloh made contact on his own with ISIS members in Africa earlier this year.
The ex-soldier was planning an attack like the one in Fort Henry in which 13 people were killed by a gunman in 2009.
In addition to his trip to Africa and contact with a now deceased member of the Islamic State, Jalloh also tried to donate $500 to ISIS. This money was intercepted by an FBI agent.
According to the AP, Jalloh left the Army National Guard after hearing lectures from radical cleric Anwar al-Awlak. Jalloh worked as a specialist in the 276th Engineer Battalion, 91st Troop Command from 2009 to 2015 when he was honorably discharged.
Over the past few months, Jollah spoke with someone he thought was a member of the Islamic State but was actually an FBI informant.
"Sometimes, you just have to take action," he said to the informant. "You can't be thinking too much. You have to pick an action and take it."
"Prosecutor John Gibbs said at Tuesday's hearing that Jalloh faces up to 20 years in prison if convicted," the AP says.