Belgium is a lovely country. Flanders, in the north, has some of the prettiest towns in Europe. Wallonia, to the south, has lush forests and picturesque valleys. This partition, alas, also comes with an ethno-linguistic segregation that has torn Belgium apart and may have even helped make it an epicenter of terrorism. Americans take heed.

News that Belgium is in its second day of a total clampdown because of the threat of terrorism is hard to take. I spent almost six years there in the late 1990s and early 2000s writing for the European edition of The Wall Street Journal. In that time, I got to know Belgium well. I have fished the Meuse, biked with my wife in Bruges and nearly hit a very large boar that jumped in front of my car one night in the Ardennes.

More importantly I talked to many, many people from all walks of life. Bartenders, cabinet ministers, neighbors, businessmen, journalists. I immersed myself in the culture with relish.

After being there for only a short time I took to asking nearly every North African immigrant I met, or their Belgian-born children, if he or she felt Belgian. The reason was that their estrangement from the country and disaffection with their co-citizens were palpable.

I never heard yes. Not once. Finally, one of them clarified things for me. “Nobody here wants to be Belgian. Why should I be the only one?” he shrugged.

What he meant was, the Dutch-speaking Flemish and the French-speaking Walloons (never mind the German-speakers in the southeast) don’t really think of themselves as compatriots. In fact, there’s no love lost between them.

Wags say that what holds the country together is the soccer team and the royal family, but in reality it is the central government’s determination not to let the Flemings—who pay a disproportionate share of the taxes—go their own way.

It’s important we bear this in mind as all eyes turn to Belgium after it was discovered that its gritty Molenbeek district was home to the suspected ringleader behind the Paris terrorist attacks that killed 129 on Nov. 13, Abdelhamid Abaaoud. Three of the eight terrorists had ties to Molenbeek, where the Muslim population may be over 50 percent and youth unemployment as high as 40 percent.

Belgium’s—and Molenbeek’s—centrality in European jihadism has become even more apparent as police have launched several raids and made arrests in Molenbeek, and Belgium’s Prime Minister Charles Michel has finally asked for constitutional changes to make arrests easier. Police say that Abaaoud was one of those killed this week in a raid in the Paris neighborhood of St. Dennis.

Belgium has many things going for it. Its capital, Brussels, is headquarters to the European Union and the North Atlantic Treaty Organization, two of the largest international organizations in the world. Not coincidentally, Brussels’ restaurants are top quality—“French food, German portions!”—as are its chocolatiers, sidewalk cafes and beer (over 1,000 different brands in a country the size of Maryland).

But its linguistic schizophrenia has rendered Belgium dysfunctional. Even the Belgian Justice Minister Koen Geens admits that the country’s divisions make surveillance hard. It often appears that one half of the country literally does not speak to the other side. And, it’s not just an administrative problem, but one of a disjointed national identity. 

“We are living in a divided country,” a Molenbeek academic who studies international Jihadism told the German magazine Der Spiegel this year. “The clear structures of an Islamic theocracy are thus more attractive to many.”

The Der Spiegel correspondent had traveled to Molenbeek in January to find out why a country of 11 million had sent an estimated 440 to fight in Syria, whereas Britain, with 60 million people, and Germany with 80 million, had respectively sent 500 and 600.

Obviously the police and the political leaders should have asked themselves the questions Der Spiegel was asking back in January, and taken the necessary steps. Socialist economics have also not helped a country whose industrial base is disappearing.

But linguistic separatism has not worked. It already would have been difficult to assimilate Moslem immigrants, especially fundamentalist ones, into a majority Catholic country with little history of religious pluralism. Belgium’s decision to segregate itself rather than pursue national unity has made the process all but impossible. And this is the lesson for Americans.

Consider two items in the news this week. U.S. Citizenship and Immigration Services announced that it was offering its civics practice test for aspiring citizens in Spanish. Meanwhile, the state of Hawaii, is moving ahead with plans to hold elections that are plainly racially discriminatory, to elect a separate government that excludes all non “Native Hawaiian.”

National unity has given us a uniquely American culture and national character that have served country—and the world—well for over two centuries. Linguistic and ethnic segregation just does not have a good record—as we can see in the sadly empty streets of Brussels under the threat of terror.