"In his guilty plea, Booker admitted he intended to kill American soldiers and to assist ISIS’s [Daesh’s] fight against the US," the release stated.
Booker intended to build a car bomb and blow up the vehicle with himself in it during the attack, according to the Justice Department.
He pledged allegiance to Daesh leader Abu Bakr al Baghdadi and filmed a video that was to be released after his death.
The FBI began investigating Booker in 2014 following social media posts he made, claiming he tried to enlist in the US Army to commit an "insider attack" against soldiers.
Booker pleaded guilty in February 2016 to one count of attempting to use a weapon of mass destruction and one count of attempted destruction of government property by fire or explosion.