KRCG reports Robert Lorenzo Hester, of Columbia, entered his plea Monday to providing material support or resources to terrorists.
Federal prosecutors charged Hester in February 2017 after a monthslong FBI investigation.
An affidavit released at the time said undercover agents posing as Islamic State sympathizers met with Hester several times. At their request, he provided materials such as nails and duct tape that he believed would be used to create bombs.
An FBI employee told Hester the attacks were planned for Presidents Day in Kansas City.
Hester received an honorable discharge from the U.S. Army in mid-2013 after serving for less than a year.