Opening arguments in the first terrorism-related trial of suspects apprehended after the Sept. 11, 2001, attacks began today with widely divergent descriptions of the four defendants and the behavior that brought them to government attention.

The government alleges the four defendants conspired to obtain weapons, secure fake identification for religious zealots and blow up U.S. targets. It says audiotapes found in their apartment show their religious fanaticism and a videotape located there represents the fruits of a scouting mission for a terrorist attack.

"This is not a case about young Arab males coming to live the American dream," said Assistant U.S. Attorney Richard G. Convertino.

That statement was met with biting sarcasm by defense attorneys. They said their clients -- Farouk ali-Haimoud, Ahmed Hannan, Karim Koubriti and alleged ringleader Abdel-Ilah Elmardoudi -- were on trial because the government had twisted innocent actions into something much more sinister.

"These guys were of Arab descent, and they were immediately suspect," said James Thomas, Hannan's lawyer, brushing aside the government's case.

The sparring before the jury follows months of legal battles in a case that began 18 months ago, when federal agents stumbled on what they now contend is a "combat operational sleeper cell" while searching for another man.

The case has become nationally significant, because the Detroit suspects are the first to face terrorism-related charges before a jury. Several other cases have ended in plea agreements, including admissions this week from two Yemeni Americans in Lackawanna, N.Y., that they had traveled to al Qaeda terrorist camps and received training.

The defendants were part of the government's nationwide roundup of 1,200 people after the Sept. 11, 2001, attacks, a law enforcement campaign that created an outcry from leaders of Arab American and civil liberties groups. They charged that the government indiscriminately locked up young Arab males in its war on terrorism.

Similar concerns have been part of this trial. Defense attorneys have contended the tight security surrounding the proceedings gives jurors the impression that their clients are dangerous. They also tried unsuccessfully to have the trial postponed until after the war with Iraq, which they said might prevent a fair trial for their clients.

U.S. District Judge Gerald E. Rosen acknowledged the trial's potential impact in court today. "This is a particularly important trial, and many people are watching our judicial system to see if we can give a fair trial . . . in these challenging times."

Convertino said the men were planning to blow up American targets, and referred to a videotape of Disneyland and Las Vegas that prosecutors contend was the result of a scouting effort for a potential attack.

Convertino said the men also used deception to hide their phone calls to other countries and conceal large sums of money wired to one of them from Amsterdam.

He said that when authorities first encountered the men on Sept. 17, 2001, a voluntary search of the apartment three of them shared resulted in the confiscation of forged passports, visas, Social Security cards and photos and 105 audiotapes that authorities said were filled with hateful references to Christians and Jews.

Meriem Ladjadj, ali-Haimoud's mother, listened intently to the proceedings in the courtroom today. She was particularly distressed by prosecutors' characterization of the tapes.

"If they find him guilty because of those tapes, then they have to imprison every single Muslim, starting with me first," she said.

Most alarming, authorities have said, was a day planner found in the apartment that contained a sketch of a U.S. airbase in Turkey, notes regarding a military hospital in Jordan and a reference to a "foreign minister." Authorities believe the notation was a reference to former Defense Secretary William S. Cohen, who canceled a trip to Turkey's Incirlik Air Base in 2000 after intelligence sources warned of a possible attack.

Three of the four defense attorneys delivered opening arguments today, all saying the government is distorting the facts in the case. They also charged that the government's chief witness, Youseff Hmimssa, is a lifelong criminal whose testimony cannot be believed.

Hmimssa, a former roommate of the defendants', was wanted on separate credit card charges. "He lived a life of lies," said Robert Morgan, ali-Haimoud's attorney.

Mentioned almost in passing today was Nabil Almarabh, the former Boston cabdriver whose name appeared on an FBI terrorism watch list and brought authorities to the rundown apartment where they found three of the defendants. Defense lawyers said their clients were in the wrong place at the wrong time, and authorities took them in when they could not locate Almarabh.

The case is expected to last four to six weeks. Jurors are not sequestered but have been warned against watching news reports or talking about the case.

This artist's rendition depicts the four defendants, at left, and defense attorney William Swor before U.S. District Judge Gerald E. Rosen in Detroit.