With France's deadly attacks, Islamic terror has apparently struck once more in the heart of Europe _ and authorities say there's a dangerous twist: the emergence of homegrown extremists operating independent of any known networks, making them hard to track and stop.
"We have a different kind of jihadist threat emerging and it's getting stronger," Europol chief Rob Wainwright told The Associated Press in a telephone interview from The Hague. "It is much more decentralized and harder to track."
France's motorcycle gunman traumatized a nation heading into presidential elections and spread fear across the continent that the specter of al-Qaida was once again threatening daily life.
Mohamed Merah, a 23-year-old Frenchman of Algerian descent, sowed his terror over the course of nine days, killing paratroopers, Jewish children and a rabbi. He died Thursday in a shootout after police raided the Toulouse apartment where he had been holed up.
Merah traveled to Afghanistan and Pakistan and had claimed to have trained with al-Qaida there, but French authorities said Thursday they had no evidence that he had any contact with terrorist groups or that al-Qaida had ordered the killings.
Wainwright warned that Europe faces a tough challenge ahead.
Combating individuals acting in apparent isolation, he said, will take smarter measures in monitoring the Internet, better intelligence and international cooperation in counterterrorism efforts.
And he conceded there were limits to what law enforcement officials can do. "We can't police the Internet," he said.
Other European terror authorities echoed that view, saying that apprehending suspicious individuals with no clear connections to terrorist networks is legally problematic.
"We have one law for war, one law for peace, but we don't have a law for the current situation," said Alain Chouet, a former intelligence director at France's DGSE spy agency.
"If we stopped (Merah) three weeks ago, what would people have said? 'Why are you stopping him? What did he do?'"
German officials expressed the same frustration in the case of Arid Uka, a Kosovo Albanian who gunned down two American airmen and wounded two others last year at the Frankfurt airport before being captured. Aside from illegally acquiring a handgun, the 22-year-old, who was convicted last month, had committed no crime until he shot his first victim in the back of the head.
"A group preparing an attack with bombs or other instruments is running the danger of being detected," said a high-ranking German intelligence official, speaking on condition of anonymity because of the sensitivity of the issue.
"A single person or a group of two, they have a greater chance of not being observed by security forces or getting tracked by police. It is very hard to find individuals like this and stop them from acting."
Some experts believe that al-Qaida's new strategy is, in fact, to stop acting like a network.
Encouraging individuals to carry out terrorist attacks, without organizing them in cells, has become integral to the terrorist organization's modus operandi, said Noman Benotman, a former jihadist with links to al-Qaida and who now works for the London-based Quilliam Foundation.
"They are part of the overall al-Qaida strategy, and they are part of the instructions _ or suggestions, if you will _ for groups and individuals seeking guidance or inspiration," he said.
Benotman, who maintains contact with the jihadist community, said that since the death of Osama bin Laden, al-Qaida's strategy has evolved to include more individual attacks, rather than the heavily choreographed and expensive operations seen in the Sept. 11 attacks or the London suicide bombings in 2005.
The German intelligence official noted that al-Qaida theorist Abu Musab al-Suri published a book about 10 years ago putting forth the strategy of "leaderless resistance." The official said that with Internet propaganda, "you don't need any teacher or some other person any more to push people toward these actions."
Wainwright also sees al-Qaida's hidden influence in the France attacks.
"He was acting in line with al-Qaida inspired tactics, and although it may not have been closely coordinated, it was certainly al-Qaida inspired," he said.
Wainwright said Merah lacked the professionalism of terrorists of the past. He said the gunman seemed divided between wanting to increase his death toll and publicizing his acts by filming his deeds and bragging about them.
"It is very telling that he filmed his exploits," he said. "Still, in spite of the mistakes, he managed to carry out significant damage. ... That is the challenge for us."
A British security official said the key to targeting this brand of individualized terror was figuring out whether people were simply thinking extremist thoughts or would truly turn violent.
"We prefer the term self-starting over lone wolf," the official told the AP on condition of anonymity because of the sensitivity of his work.
"But the reality is that there are hosts of people like this out there and most of them will never do anything. You have to have information to suggest they are about to do something. Unfortunately, there are no thought police."
There are, nonetheless, plenty of recent examples of the dangers of terrorists working in isolation:
_ Maj. Nidal Hasan, a U.S. Army psychiatrist accused of killing 13 people during the Fort Hood, Texas, shooting rampage in 2009.
_ Taimour Abdulwahab, an Iraqi-born Swede, who targeted Christmas shoppers in Stockholm in December and blew himself up.
_ Umar Farouk Abdulmutallab, who was sentenced last month to life in prison after admitting he attempted to blow up an international flight with a bomb in his underwear as the plane approached Detroit on Christmas 2009.
President Barack Obama said last summer that a "lone wolf" terror attack in the U.S. is more likely than a major coordinated effort like 9/11.
In the case of Merah, it's still too early to know whether he was acting alone or had outside support.
Authorities are trying to determine whether Merah's 29-year-old brother, Abdelkader, was involved, and are searching for accomplices who might have encouraged Merah to kill or furnished the means to do so.
Merah told negotiators he killed to avenge the deaths of Palestinian children and to protest the French army's involvement in Afghanistan as well as France's law against the Islamic face veil.
French authorities have acknowledged that Merah had been under surveillance for years and that his travels to Afghanistan and Pakistan were known to French intelligence, raising the question of whether security services might have been able to act against him before he was able to carry out his attacks.
German Interior Minister Hans-Peter Friedrich told German media that there were striking similarities between the Uka and Merah attacks, and that it drives home the need for a "security partnership" between intelligence services and Muslim groups and communities.
"We need them to report the first signs," he said. "We need the help of society."
Associated Press writers Thomas Adamson in Paris, Michael Corder in The Hague, Karl Ritter in Stockholm, Eileen Sullivan in Washington, Jan Olsen in Copenhagen, and Victor Simpson in Rome contributed to this report.