There is no doubt that the US has taken the fight to al-Qaeda, in Afghanistan and elsewhere, after the September 11 terrorist attacks.

Even those who accuse the US of using heavy handed tactics, from the prison in Guantanamo to the CIA practice of rendering prisoners to countries where they might be tortured, there have been great successes in the fight against al Qaeda.

Although Osama bin Laden, the terror network’s leader, has still not been brought to justice, many other members of alQaeda have been captured or killed. These do not just include foot soldiers but also some of the group’s top leaders.

But the suspects that were arrested in Miami and that are accused of plotting to blow up the Sears Tower in Chicago — the country’s tallest building — had no apparent connection to al-Qaeda.

FBI Director Robert Mueller on Friday spoke of "the changing shape of terrorism" that results in new threats from homegrown terrorists.

"While we have made great strides in disabling traditional terrorist models like al-Qaeda," Mueller said, "the convergence of globalization and technology has created a new brand of terrorism, and today terror threats may come from smaller, more loosely defined individuals and cells who are not affiliated with al-Qaeda, but who are inspired by a violent jihadist message."

These groups, Mueller added, "may prove to be as dangerous as groups like al-Qaeda, if not more so."

To drive home the point of a new brand of terrorism, Attorney General Alberto Gonzales used pretty much the same words in a press conference on the alleged Miami terror plot.

"The terrorists and suspected terrorists in Madrid and London and Toronto were not sleeper operatives sent on suicide missions," Gonzales said. "They were students and business people and members of the community. And they were persons who, for whatever reason, came to view their home country as the enemy."

US law enforcement officials noted that these new terrorists operate "under the radar screen." Instead of relying on funding from terrorist donors abroad, they get money by committing low level crimes, Mueller said Friday.

The US is operating a database of 200,000 known or suspected terrorists, but that list might still not encompass a radical who one day decides to become a militant.

The Internet plays a key role that allows potential terrorists to obtain or pass on information in relative anonymity, Mueller said.

"There are between 5,000 to 6,000 extremist Web sites on the Internet encouraging extremists to initiate their own radicalization and to cultivate relationships with other likeminded persons," the FBI chief said.

Mueller also pointed out that homegrown terrorist cells can gain hold in many different settings.

"The evolution from extremism to terrorism can take place just about anywhere, from academic settings, prisons and community centers to the Internet," Mueller noted.

The FBI chief said that a global effort is needed to fight terrorism and that intelligence is a key to finding these small groups as they emerge and before they can strike.

"There is no one person, no one agency, no one police department, indeed no one country that has all of the answers," Mueller said.

"Our greatest weapon against terrorism is unity," Mueller stated.

"And that unity is built on information-sharing and coordination among our partners in the law enforcement and the intelligence communities."