BRUSSELS, Belgium – A clash of civilizations may be taking place on the battlefields of Iraq and Afghanistan, but it's also happening a lot more quietly in European cities.
Old Europe's population is dwindling even as immigration and high birth rates among Muslim groups are swelling in cities all over the continent.
And in Belgium, it is no different.
Filip Dewinter, a leader of the far-right separatist party Vlaams Belang, predicts there will eventually be a kind of civil war when the longtime residents of Brussels — the nation's capital and administrative seat of the European Union — realize their city is about to be taken over by Muslim immigrants.
• Click here for video.
Although there are no official statistics on how many Muslims live in Brussels, it is believed they make up about 25 percent of the city’s 1 million urban residents. Dewinter, who opposes immigration and has called Islamophobia a "duty," claims three of the 19 sections of Brussels, each with its own mayor, now have Muslim majorities.
"In those neighborhoods it's not our government that's in power," he said, "but the Muslim authorities — the mosques, the imams — who are in charge."
FOX News visited one of those neighborhoods, called Molenbeek, which looks more like North Africa than the heart of Europe.
For some Belgians, that's not a problem. The mayor of Molenbeek, Socialist Philippe Moureaux, has worked hard to help Muslims try to integrate over the past decade and a half.
Moureaux believes multiculturalism is a good thing. He says even those who disagree with him should get used to life as it is in Brussels today: "Be realistic. They're here. They're relatively numerous and they're growing."
Many Moroccans have been in Belgium for decades and are now citizens, as are their children. The imam of one of the main mosques, which thousands of young Moroccans attend each Friday, stressed that Muslim immigrants have starting blending in around Brussels.
During FOX News' brief visit, there were no fiery demonstrations of the kind that have wracked the Netherlands, though the municipality is sometimes considered dangerous to traverse at night.
Yet Molenbeek remains disconcerting. Belgian police assigned three plainclothes officers to watch over a FOX News team shooting street scenes one morning in Molenbeek. When FOX News returned in the afternoon as more people were out and about, the police said it would be safer not to get out of the car. It wasn't even dark yet.
Part of that fear stems from particularly nasty street crime, something that can happen in bad neighborhoods in any big European — or American — city. But part of it is due to strong anti-Western sentiment among Belgium's Muslims, which suggests that true integration is still a long way off.
Mayor Moureaux blames the problems on a tiny number of very violent youths who are condemned by everyone, including the Muslim community.
But for Dewinter, integration simply isn't working. He claims the great majority of the Muslims don't want it to work. So instead of being a melting pot, Brussels has become a city that does everything possible to appease Islam, he claims.
"Halal food is served in the schools, not only for Muslim children, but for all the children," said Dewinter, adding that municipal pools in Brussels now have separate hours for men and women to swim.
The anti-immigrant Vlaams Belang, once considered a pariah party, now controls about 24 percent of the Belgian vote, a trend matched in other European countries with burgeoning Muslim populations.
Though the immigration debate has not yet reached the fever pitch it has in the U.S., a real test will come when a major European city has a Muslim majority. The first could be Marseilles, in France, or Amsterdam, in the Netherlands. But don't count out Brussels, the heart and capital of Europe.