An 18-year-old suburban Chicago man, who the authorities say was enamored with Osama bin Laden and intent on killing Americans, has been arrested after attempting to detonate what he thought was a car bomb outside a Chicago bar, officials said Saturday.

There was never any danger that the suspect, Adel Daoud, would actually detonate a bomb. The plot, which ended with Mr. Daoud’s arrest on Friday, was proposed by undercover F.B.I. agents posing as extremists, according to a statement released by the United States attorney’s office in the Northern District of Illinois.

Mr. Daoud, a United States citizen who lives in Hillside, Ill., on the outskirts of Chicago, has been under surveillance for months, and in multiple conversations with agents expressed a desire to kill on a mass scale as revenge for what he believed was the persecution of Muslims by the United States, according to court papers.

In one conversation recorded by the authorities, Mr. Daoud said he wanted the attack to be “massive” enough to “make it in the news like tonight.”