MIAMI -- Opening arguments began Tuesday in the trial of seven Miami men accused of plotting to blow up the Sears Tower in Chicago and several buildings in Miami.

Prosecutor Richard Gregorie told the jury this case was about jihad, saying the seven men had the "sole purpose of creating a holy war against the United States."

The suspects, known as the Liberty City Seven, were charged after a lengthy investigation in which an FBI informant posed as an al-Qaida member and led the seven in a pledge to the terrorist group and Osama bin Laden.

Gregorie told the jury the government will use audio and video recordings to prove the men planned to plant bombs at the FBI building in North Miami Beach and at the federal court complex where the trial is being held.

Defense attorneys are expected to argue that the suspects were led into the plot by the FBI informant and were only hoping to possibly extort money from him and not commit acts of terror.

Ana Jhones, the attorney for accused ringleader Narseal Batiste, said in her opening statements that the defendants were taken in by the government informants.

"This case is about an orchestrated event -- a play," Jhones said.

But Gregorie countered, saying the videos clearly show each man swearing an oath to al-Qaida.

"They do it voluntarily," Gregorie said.

The trial is expected to last two months or more and the suspects could face up to 70 years in prison if they are found guilty.