A crucial feature of European politics, especially since the end of the Cold War, is based on the assumption that the nations of Central and Eastern Europe hunger to be part of the continent’s economic and political integration process. That process is symbolized by the European Union and its predecessor, the European Economic Community. A subsidiary assumption is that prospective new members will be willing to modify their domestic and foreign policies, including abandoning narrow nationalist agendas, to maximize their prospects for membership.

Until a few years ago, those assumptions seemed reasonable, although pro-integrationists in Europe even at that time tended to underestimate the continuing potency of nationalist sentiments in some regions, especially the Balkans. But given the financial fiasco in the EU in the past two years, EU partisans now seem to be significantly overrating the appeal of membership to prospective candidate nations. Yet that message does not appear to have penetrated the thinking of either Western political leaders or pundits in the policy community.

The ongoing financial debacle could retard further expansion of EU membership in two ways. First, countries outside the EU might well wonder whether it makes all that much sense to seek to join an association that is experiencing such woes. Second, the leading EU powers might well wonder whether it makes sense to admit more small, relatively poor candidates from Eastern (especially Southeastern) Europe that might turn out to have the same weaknesses—and cause the same headaches—as Greece, Portugal, Spain and other troubled current EU members.

True, there are still significant benefits to EU membership. The existence of a huge market with minimum trade barriers has been the principal appeal since the integration process began more than six decades ago, and that benefit has grown with time. But it is no longer an unalloyed benefit, and the EU’s growing problems are likely to be taken into account in the capitals of both current and prospective member states.

The EU is still the great brass ring of European politics, but it is now a tarnished brass ring. That development has strategic as well as economic implications. Will the Balkan countries really submerge their ethnic antagonisms simply to gain admission to a troubled European Union? Will Turkey soften its policy toward Cyprus to increase its odds of becoming part of the EU? Policies based on the assumption that the answers to such questions are an unequivocal “yes” are dubious at best. Turkey’s recent belligerent reaction to off-shore drilling plans by Cyprus clearly raises doubts on that score. The stirring of renewed secessionist sentiments in Bosnia does the same.

Yet both U.S. and EU leaders still cling to the twin expectations that the EU will remain eager to expand its roster and that the carrot of EU membership will be sufficient to dampen ethnic tensions and eclipse narrow nationalist goals. They need to ask themselves what happens if any key aspect of their expectation proves false. That question is especially pertinent for U.S. policy makers, if the United States wants to avoid being dragged once again into dangerous geopolitical tensions in the Balkans or the Eastern Mediterranean.

Ted Galen Carpenter, senior fellow for defense and foreign policy studies at the Cato Institute, is the author of eight books on international affairs, including Bad Neighbor Policy: Washington's Futile War on Drugs in Latin America. He is also a contributing editor to The National Interest.