PARIS - More than decade after the end of the Balkan wars, Croatia has become the 28 ^th member of the European Union as of Monday, July 1 , 2013. This is undoubtedly a positive sign for Europe as the old continent faces a new wave of euro-skepticism .

Europe remains attractive despite the rise of individual nationalisms. This new membership, following Slovenia, is also another way to offer closure after Europe's failure to end the terrible massacres in the former Yugoslavia without the decisive intervention of the United States.

So what happens next?

Everyone knows this won’t be the last member to join the EU. Serbia wants to open adhesion negotiations in January and Kosovo hopes it will soon be granted a Stabilisation and Association Agreement, the first step towards adhesion. The other applicants are Macedonia, Bosnia and Herzegovina, Montenegro and Albania .

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Ever-expanding Europe - Source: Kolja21

Meanwhile, Iceland has already started negotiating for membership -- and Georgia, Ukraine and Armenia are all dreaming of joining the Union. And we should not forget the particular case of Turkey.

Yet, the EU may face traps if it keeps expanding. The union is already mostly ungovernable in the face of its 27 members. Every single matter from Europe’s budget to the European Commission's mandate to – finally - start negotiations on a free-trade agreement with the U.S. inevitably leads to internal arguments among members. The EU has never been able to find an agreement on the war in Syria. So how will it be able to make decisions with a single voice in front of America, China , Russia or even India ?

Of course, as far as money’s concerned, the integration of the countries of former Yugoslavia would only cost 10 billion euros to the European budget. But there is still a great divide in lifestyles between those countries and the rest of the Union. For many of the new applicants, joining the EU is considered more like a renewal of their commitment towards the Atlantic Alliance -- not a sudden awareness of a true European identity .

The old continent is slipping towards a Europe with variable geometry, including countries that should have been integrated with the first 17 of the euro single currency zone (a process that is still very problematic), the 22 of the Schengen area (a flawed area as well) and the others.

The EU needs to finally settle its borders and redefine its raison d’être . Even if today, by welcoming Croatia, it can brag again a bit about fulfilling the objective of its founding fathers: “Make peace reign in Europe.”