The unidentified suspect was arrested in Cleveland, Ohio over the weekend.
VIDEO: FBI discusses arrest in connection to terror attack planned for Fourth of July in Cleveland
ABC News has learned the plot involved detonating a bomb around Independence Day, but that's all they're revealing at this time.
During a press conference Monday, FBI officials said the "suspect conducted surveillance in Cleveland and also expressed interest in 'chopping off heads and hands and disposing of bodies."'
This is a developing story, check back for updates.