Law enforcement officials and security experts are warning against the threat of homegrown terrorism as several cases involving alleged American jihadists enter the courts.
"The public is getting complacent," New York City Police Commissioner Ray Kelly tells FOX News. Kelly, who was the police commissioner during the first World Trade Center bombing in 1993, has developed a task force of counterterrorism officers trained to spot jihadists.
Although there has not been a major terrorist strike in the U.S. since Sept. 11, 2001, Kelley says the country cannot let down its guard.
"We can't afford to be complacent in law enforcement, and I don't think we are," Kelly says in the new FOX News documentary, "Jihad, USA," which will air at 9 p.m. ET on March 29.
Several terror-related cases now in the courts highlight this need for continued vigilance, experts say.
— In Florida, the retrial of six of the "Liberty City Seven" is coming to a close. The group members, who allegedly plotted to destroy the Sears Tower in Chicago and swore allegiance to Al Qaeda on a secret FBI surveillance tape, were arrested in June 2006. Their first trial ended in a not-guilty verdict for one defendant and a mistrial for the other six.
— In Washington state, the murder trial has begun for Pakistani-American Naveed Haq, who is accused of opening fire in Seattle's Jewish Federation Building in July 2006, killing one woman and wounding five others. Haq allegedly said he was mad at the Jews and how they are running the country.
Two other cases are to enter court next month.
— In Michigan, a preliminary hearing is scheduled for Houssein Zorkot, a Lebanese-born medical student at Wayne State University in Detroit who posted on his Web site in September 2007 that he was launching a personal jihad. He was arrested that same day in a nearby park, wearing camouflage paint and holding a loaded AK-47.
— In South Carolina a trial is set for Youssef Megahed and Ahmed Mohamed, two University of South Florida students who officials say had pipe bombs in their car when they were caught speeding near the Goose Creek weapons base.
Terror experts say these and other cases since Sept. 11 illustrate an emerging threat from homegrown terrorists, people who have been radicalized by extreme Muslim doctrine within the U.S.
"Al Qaeda is depending today upon the spontaneous emergence of these jihadist cells that are not tethered to the leadership of Al Qaeda by either telephone or e-mail," terror investigator and author Steve Emerson told FOX News.
But others say the threat of homegrown Islamic terrorism is overstated.
In "none of these cases brought in the United States did the government ever produce any evidence suggesting that someone had prepared a bomb," says Jim Wedick, a former FBI agent. "Someone's actual ability to do harm needs to be taken into the equation."
Wedick consulted with the defense on the Liberty City Seven case.
"The solution is not to treat the whole Muslim community as a suspect community," says Hussam Ayloush, a spokesman for the Council on American-Islamic Relations. "This is not about ignoring a threat, but this ... should not be about exaggerating any threat in a way that promotes certain political agendas."
Kelly says the threat is real and the only way to combat it is through prevention.
"Just imagine if the 19 hijackers on Sept. 11 were arrested on Sept. 10," he says. "How would that have been characterized?"
"Jihad, USA," a new FOX News documentary hosted by E.D. Hill, airs on the FOX News Channel at 9 p.m. ET on March 29.