Mohamed Jalloh, 27, a naturalised US citizen, pleaded guilty in October 2016 to providing material support to a foreign terrorist organisation.
Jalloh told investigators he had also tried to travel to Libya and considered a shooting attack against US soldiers.
In September 2016, another soldier was sentenced for supporting the group.
Former National Guard specialist Hasan Edmonds was given 30 years in prison for planning an attack against soldiers at the Joliet Armory in Illinois.
