In Bridgeport, Frederick Forcellina was charged with threatening to use a weapon of mass destruction against federal courts in Stamford, Bridgeport and Norwalk.
An FBI affidavit quoted the suspect as calling 911 and making the threats.
"This is not a hoax. And I'm telling you that three of your symbols of justice, the court buildings ... have been dusted," the caller said.
"This is no joke. We are tired. We are going to turn around and do the railroad stations and maybe even some schools, as horrid as it may sound."
Authorities traced the call to a pay phone where Forcellina was confronted. The FBI said Forcellina admitted he made the call.
Federal convictions carry sentences of up to five years in prison for hoaxes or other threats involving weapons of mass destruction.
Attorney General John Ashcroft said earlier that another Connecticut man had been indicted on charges of allegedly making false statements in connection with an anthrax scare at the state Department of Environmental Protection.
Ashcroft said Joseph Faryniarz sat by when officials found a white powder on a paper towel on his desk last week, even though he knew the powder was a hoax. He also tried to blame co-workers, Ashcroft said.
"It should be painfully obvious to every American today that the threat of bioterrorism is no joking matter," Ashcroft said. "Every threat is real. The perpetrators of hoaxes should know that penalties are real."
Faryniarz would face up to five years in prison and up to $3 million in fines if convicted.