MIAMI — Seven men intended to destroy Chicago’s Sears Tower and bomb FBI buildings to ignite a guerrilla war that would overthrow the American government and pave the way for an Islamic regime, federal prosecutors said yesterday in opening statements.

FBI audio and video recordings show that the so-called “Liberty City Seven” hoped to use street gangs as soldiers who would stage attacks, ranging from large-scale bombings of major buildings to poisoning salt shakers in restaurants, Assistant U.S. Attorney Richard Gregorie said.

On one of the 15,000 FBI recordings, Narseal Batiste is overheard saying he would make sure no one survived destruction of the 110-story Sears Tower because his soldiers would be ready to shoot down anyone who escaped.

“These defendants wanted to wage jihad against the United States, and they tell us so in unequivocal detail,” Mr. Gregorie told jurors. “They say ‘the war has to be fought here. And it can’t be just a bombing. It’s got to be chaos.'”

Batiste attorney Ana Jhones countered that the purported plot was driven mainly by two paid FBI informants, including one known as Mohammed who posed as a representative of Al Qaeda. She said Mr. Batiste’s group was coerced into going along with the violent plan by “this great con man,” who was paid about $80,000 by the FBI.

“This case is about an orchestrated event, a play,” Ms. Jhones said. “These two informants knew how to work the system. They wrote the script.”

Each of the seven defendants from Miami’s impoverished Liberty City neighborhood faces up to 70 years in prison if convicted of all charges, including conspiracy to levy war against America and conspiracy to provide material support to Al Qaeda. All seven have been in custody since their June 2006 arrests.

Evidence against the group includes a March 2006 ceremony, recorded by the FBI, in which each man swears allegiance to Al Qaeda and Osama bin Laden. Members of the group also took pictures of the FBI office in Miami and other government buildings they were told Al Qaeda was interested in targeting in a separate plot.

“In this case, all of the conspirators, on tape, walk up, take this oath, give their name, and swear their loyalty to a foreign terrorist organization,” Mr. Gregorie said. “They do it voluntarily.”

The other informant, known as Abbas, contacted the FBI in October 2005 after Mr. Batiste allegedly asked him if he had any contacts in his home country of Yemen to help with the supposed terrorism plot.

Mr. Batiste, a 33-year-old construction worker, was leading the Miami chapter of a sect called the Moorish Science Temple, which does not recognize the authority of the American government.

Ms. Jhones described Mr. Batiste as a “wannabe religious leader” who hoped to form a nonprofit group to help people in his crime- and drug-ridden neighborhood, with part of that including martial arts training aimed at instilling a sense of discipline among his group. They operated out of warehouses in the neighborhood.

After their arrests, Mr. Batiste and some other group members told the FBI they only went along with Mohammed in hopes of extorting money from him. Mohammed had offered the group $50,000 along with supplies and other goods, and Ms. Jhones said they hoped to con Mohammed out of it.