Two Georgia men have pleaded guilty to conspiring to get an unregistered explosive and an illegal gun silencer in what prosecutors describe as a plot to attack government targets.

The suspected ringleader of the group, 73-year-old Frederick Thomas, and 67-year-old Dan Roberts entered their pleas Tuesday in federal court in Gainesville, about 55 miles northeast of Atlanta.

They could face up to five years in prison and a 250,000 fine. They also agreed to cooperate with authorities.

They are among four men arrested in early November after at least seven months of surveillance by an undercover informant who infiltrated their meetings at a Waffle House, homes and car rides.

The government's case is pinned on dozens of hours of recordings the informant made.

Tags: terror suspect, Georgia militias, militia, Georgia militia plot, guilty plea