Five men charged with plotting to bomb a US bridge placed what they thought were real explosives at the site and repeatedly tried to detonate them using mobile phones, according to the FBI.
Federal authorities described the men as anarchists who are angry with corporate America and the government and unknowingly worked with an FBI informant.
The FBI said suspects bought fake explosives from an undercover employee and put them at the base of a highway bridge south of central Cleveland on Monday.
They allegedly tried to set off the explosives using a text-message detonation code, then calling the person who provided the bombs to check the code when it failed.
All five are charged with conspiracy and trying to bomb property used in interstate commerce. They were remanded in custody until Monday. The charges carry possible penalties of more than 20 years in prison.
The suspects had been associated with the anti-corporate Occupy Cleveland movement but do not share its non-violent views.
The alleged plotters were frustrated that other anti-corporate protesters opposed violence.