Federal authorities say the suspects arrested in an alleged plot to blow up a bridge near Cleveland had discussed other potential targets, including a law enforcement center, oil wells, a cargo ship or a new downtown casino.
An affidavit indicates that federal authorities worked with a confidential source who began making contact with the suspects in October and recorded conversations with them over the past three months.
The affidavit alleges one suspect also talked about being part of group planning to cause trouble during an upcoming NATO summit in Chicago.
The FBI says three suspects are self-described anarchists. They were arrested Monday.
Authorities say there was no danger to the public because their explosives were inoperable and were controlled by an undercover FBI employee.