The Swiss electorate voted on a referendum aimed at limiting the number of foreigners that can live and work inside the country on Feb. 9. Though Switzerland is not a member of the European Union, it does have strong ties to Brussels, and changes there have repercussions throughout Europe. The measure passed with 50.3 percent approval.

The repercussions are enormous despite the slim majority. The party that pushed the referendum, the nationalist Swiss People’s Party, has extreme right counterparts in almost every country in the E.U. and the victory of an anti-immigration vote will energize their own agendas of euroscepticism and xenophobia. Powerhouse anti-immigration politicians Geert Wilders from the Netherlands and Marine Le Pen from France have already been emboldened by the triumph, calling for similar legislation in their own countries.

While it is easy to dismiss these radicals as fringe politicians who have no effect on mainstream politics, these figures have come to pose a very real threat to the stability of the last fifteen years. Le Pen won 18.6 percent of the vote in the 2012 French presidential election, the best showing ever by the anti-Muslim Front National. A poll by the French Institute of Public Opinion found that roughly 23 percent of the population would vote for the Front National in the European Parliamentary elections, more than they would vote for any other party.

The E.U. was built partly on the tenets of cross-integration, free travel and camaraderie. The ugly shadow of ultranationalism has been born from the success of the first two and the failure of the third. Europe has achieved a state of unrestrained travel between member nations, but it has not achieved the acceptance of foreign immigrants. The E.U. is now in a contradictory state in which one of its founding ideals actually threatens its unity.

The rise of these parties is dangerous to the security of Europe. The economic downturn and presence of immigrants that have been perceived as taking jobs or receiving welfare handouts have given a voice to fanatical nationalists that would like to disband the E.U. These xenophobic groups could cause the member countries to emerge more insular and ethnocentric than they originally were. Ultranationalism is polarizing in a way that is disturbingly reminiscent of the attitudes that led to the twin catastrophes of the World Wars.

Although the E.U. has made financial progress in recent years, the festering anti-immigrant hostility may be what once again plunges the area into disaster. While banning these political movements outright would be undemocratic, the international community has a responsibility to find ways to diminish their influence.

A version of this article appeared in the Wednesday, Feb. 19 print edition. Felipe De La Hoz is a contributing columnist. Email him at [email protected].