Mayor of Mechelen Bart Somers speaks to the Associated Press after early morning police raids took place in the city of Mechelen, Belgium on Tuesday, April 16, 2013. Belgian police have conducted early morning searches at numerous locations regarding the recruitment of fighters to help rebels trying to overthrow Syrian leader Bashar Assad. AP Photo/Geert Vanden Wijngaert MECHELEN, Belgium (AP) - From his city hall under Belgium's most imposing cathedral, Mayor Bart Somers is wracking his brains trying to figure out how to keep young Muslims from going to fight "holy war" in Syria against the Assad regime. Through much of western Europe, scores of Islamic youths have heeded the call to take up arms for a cause that is only a few hours away by plane. The phenomenon has alarmed authorities amid signs that the insurgency is becoming increasingly radicalized, with strong infiltration by al-Qaida. European authorities see a double danger, one that's summed up by Somers who describes the youths as "cannon fodder" in Syria - and potential "full-blown terrorists" if they make it back home alive. But it all raises a conundrum: In a free society, how can you prevent these young people from packing up and leaving? "The major challenge of each democrat is to see what we can do in the fight against fundamentalism without sacrificing our own democratic laws," said Somers. Otherwise we play into the hands of the terrorists. That dilemma was again put to the test two weeks ago when Belgian authorities organized a major anti-terror sweep seeking to weed out agitators inciting young Muslims to fight against the Assad regime. In a high-profile raid of four dozen homes, police put six people behind bars, raising criticism among some that they had overstepped their bounds by infringing on freedom of speech. In the Brussels municipality of Schaarbeek, the mayor even banned a soup kitchen for the needy, among them young Muslims, fearful that the charity workers were inciting youths to fight in Syria. The action came after two Muslim schoolboys disappeared, apparently to Syria - departures that Mayor Bernard Clerfayt linked to soup kitchen recruitment. There have been mounting calls to confiscate passports from youths who seem on the verge of leaving, something that many civil libertarians criticize as an anti-democratic restriction on movement. Those who do go to fight often leave behind distraught parents. At least one Belgian father went to look for his son, to no avail. Concerned families seek any help to prevent the outflow of young people to Syria. "We do not want people to go, especially the young men," said Abu Yamen, a Syrian who runs the El Rass pharmacy in Schaarbeek. But the daily suffering shown on television can push the young into extreme, foolhardy decisions, mayor Somers said. The fighting has exacted a huge toll on the country, killing more than 70,000 people, laying waste to cities, towns and villages, and forcing more than a million people to seek refuge abroad. It has all created an opportunity for al-Qaida to win new converts to its cause, as the hardcore Syrian regime has also tried to present itself as one of the Middle East's most secular. Insurgencies in Iraq and Libya also attracted foreign fighters. What is different in Syria is the extent to which fears are rising of the rebellion being hijacked by radical Islamist elements under the thumb of al-Qaida. At Friday prayers in Brussels, Sheikh Mohamed El Tamamy has sought to discourage youths from leaving. "Some of these youngsters think that is jihad, when youngsters go from Belgium or Holland to Syria," he said. But in truth, jihad in Islam has conditions and rules. For jihad, you must get permission from the authorities. Many Europeans, however, fear fighters coming back more than volunteers heading to Syria. The EU's law enforcement agency, Europol, said in the EU Terrorism Situation and Trend Report it published last Friday that returning fighters "have the potential to utilize their training, combat experience, knowledge and contacts for terrorist activities inside the EU." The International Centre for the Study of Radicalization, an international group of five major academic institutions, estimates that up to 590 Europeans have left, accounting for about 10 percent of the foreign fighter total in Syria. Europol said Friday that in 2012, "Syria emerged as a destination of choice for foreign fighters." This month's bombings at the Boston Marathon reinforced Europe's fears about youths leaving the West to be radicalized overseas, and coming back to carry out attacks. U.S. authorities are investigating whether one of the suspects, ethnic Chechen Tamerlan Tsarnaev, was influenced by religious extremists when he spent six months in Russia's Caucasus in 2012. U.S. Secretary of State John Kerry said after a meeting with his Belgian counterpart, Didier Reynders, that "we just had a young person who went to Russia and Chechnya who blew people up in Boston. So he didn't stay where he went, but he learned something where he went and he came back with a willingness to kill people. It's a trajectory that some Europeans fear carries parallels to the youths traveling to Syria to fight in the insurgency. "We have to follow them to protect our society," said Reynders. We have a real terrorist risk because of such behavior. In the neighboring Netherlands, anxiety has spread to the historic city of Delft, until recently known for its blue-and-white pottery, canals, and burial site of kings and queens. Now, you can add suspected jihadists as well. In the Netherlands, as in Belgium, there has been alarm over some Muslim youths leaving for Syria, with estimated departures going as high as 100. "It was known that some Delft youngsters were radicalizing," Delft mayor Bas Verkerk wrote to his city council, after unconfirmed reports that two fighters from Delft had died. And last month the nation raised its terror alert to "substantial," with the terrorism coordinator citing "signs of youngsters radicalizing in the Netherlands and the increased number of jihad travelers to Syria." As a liberal, Somers is hesitant to choose between freedom and added security and intrusion into people's lives. But he is also sensitive to the need for strong surveillance - and is seeking compromises. Somers says he wants security personnel to be "the eyes and ears in our cities" to see who plans to leave - "and then we try to influence him in a positive way." We try it with the police and the secret service. We try to find out who is behind those people," he said. Somers is now coordinating surveillance and outreach efforts with the mayors of Antwerp and Vilvoorde, which is close to Brussels. But some human rights organizations argue that fundamental rights are being trampled in the process. "We are talking about views that these youngsters hold, and you cannot change opinions with a repressive approach," said Jos Vander Velpen, the chairman of the Belgian League of Human Rights. To the contrary, they will become even more convinced, and win more status because of it. AP videojournalists Bishr Eltouni and Mark Carlson contributed to this article.