For Belgium's Jewish community, the news of the attack came out of the blue. No one had ever issued threats against the museum, which was opened nine years ago in the heart of Brussels, confirmed Julien Klener, president of Belgium's official Jewish umbrella organization, Consistoire Central Israèlite de Belgique.

And yet many in Belgium assume that the attack - taking place the day before European, regional, and parliamentary elections - was motivated by anti-Semitism. "We can't make any conclusive judgment yet, but gunfire in such a significant place suggests there was an anti-Semitic background to it," said Belgian Interior Minister Joëlle Milquet.

If that suspicion is confirmed, it would hit a country that has had comparatively few problems with anti-Semitism in the past. Maurice Sosnowski, president of the Jewish organization CCOJB, summed up the fears: "There is a lot of shock, because we witnessed the first anti-Jewish attack in Brussels since the Second World War," he said.

Open society

Together with Antwerp, Brussels is considered the center of Jewish life in Belgium. Around half of the country's 42,000 Jews live in the capital, with a rich Jewish cultural heritage - and there are 12 synagogues as well as numerous kosher shops.

Belgium has always been tolerant. In 1832, just after its founding, the state officially recognized the Jewish people as a religious community. Just as in the Netherlands, Belgians practiced religious tolerance even as Jews were persecuted in neighboring countries.

The idea that Jews were safer in Belgium was even true during the period of German occupation in the Second World War - more Jewish people survived there than in many occupied countries, not least because parts of the population had been schooled in tolerance and many Belgians took serious risks to save people's lives. As a result, more than 30,000 of the 56,000 officially registered Jews in Belgium survived the Holocaust.

The Belgian government has also taken responsibility for victims of the Shoah. In a resolution passed in early 2013, the country's Senate announced that the Belgian authorities had collaborated with the German occupiers, that this had not been worthy of a democracy, and that it had had devastating consequences for the Jewish population. A year earlier, the city of Brussels also officially recognized its role in the deportation of Jewish citizens.

Growing anti-Semitism

While such moves have been praised by Jewish organizations, many Belgians have complained of a growing anti-Semitism in society. In one recent EU study, 77 percent of Belgium's Jewish community described anti-Semitism as a very serious problem in the country - well over the European average of 65 percent. An overwhelming 87 percent of them said that anti-Semitism had increased in the last five years, and almost two-thirds said they feared they would be subject to insults and abuse in the coming months.

"Unfortunately, an attack like this had to happen, with the number of anti-Semitic slogans growing," commented Joël Rubinfeld, president of the Belgian League against Anti-Semitism (LBCA), on Saturday.

Fear of radical Islamists

Unlike the EU survey, a study carried out by the Flemish Free University of Brussels attempted to pinpoint the parts of society where this growing anti-Semitism was happening. It found that around 50 percent of Muslim students in Dutch-speaking high schools in Brussels harbored anti-Semitic opinions - for other students, the number was ten percent.

Belgian security forces are currently worried about the number of violent Belgian jihadists returning from fighting in Syria. Official figures say that 200 Belgians are fighting or have fought there - and around 50 of them have already returned.

Ahead of Sunday's election, the issue of anti-Semitism has not played a role at all yet - not even among far-right populist parties. The far-right Vlaams Belang (Flemish Interest) has distanced itself from anti-Semitic views; in fact, as the self-appointed defenders of "Judeo-Christian culture" they have a more pressing agenda against what they call the "Arab danger."