Without a doubt, the arrest of the former Bosnian Serb Army commander Ratko Mladic is a day for Serbia to celebrate, even if it came much too late. The fact that it took the reform-minded, Europe-oriented government of Boris Tadic so long to act demonstrates the clout that radical nationalists still wield in Serbia, a factor that must be taken into consideration when the European Union or other international actors deal with Serbia—on Kosovo, EU accession or just about any other issue. These elements in the secret services, military, opposition political parties and, not least, the Serbian Orthodox Church are still powerful, though less so than during the wars of the 1990s or even just eight years ago, when the liberal prime minister Zoran Djindjic was gunned down for his courageous efforts to purge those very ranks.

Mladic’s arrest opens the way for Serbia to qualify for EU candidate status, which will be a seminal moment in its transition from postwar successor of the Milosevic regimes to an authentic democracy in the Western fold. Mladic’s fugitive status was the major obstacle blocking that path, so Serbia is now on track to become a candidate—a position that Croatia, Macedonia and Montenegro already hold. Although Serbia still has one more fugitive to hand over—Goran Hadzic, a Croatian Serb—Mladic was the big fish, and with him out of the way, the country can focus on the daunting array of other problems it faces, among them rampant corruption, which is now the greatest barrier to further European integration.

Critically, the arrest was the result of unstinting EU pressure—particularly that of the Netherlands—and thus a feather in the EU’s cap, another example of how Brussels can wield power and bring about change without resorting to arms. But for this kind of power to remain effective in the Balkans, the EU has to be serious about opening its doors to the countries of Southeastern Europe. While Brussels has promised the Southeastern Europeans membership once they meet EU criteria, this—with the single exception of Croatia—will be many years in coming. The EU will be the motor and guarantor of reform in the Balkans if and only if its offer of eventual membership is credible, and the bar for it is not too high.

The trial of Mladic in The Hague, before the International Criminal Tribunal for the former Yugoslavia (ICTY), is welcome news in Bosnia too, especially to victims and the families of victims of the 1992–95 war, which was masterminded in Belgrade and carried out by the Bosnian Serb political leader Radovan Karadzic and his chief military officer, Mladic. Mladic was the bloody strategist of Sarajevo’s siege; of the 1995 Srebrenica massacre, in which some 8,000 men and boys were slaughtered; and of the overall ethnic cleansing that cost the lives of tens of thousands and displaced over a million people from their homes.

The trial of war criminals is a precondition for reconciliation in Bosnia, a slow, arduous process that has been under way for fifteen years but remains a work in progress. Moreover, putting the war’s architects on trial and convicting them before a neutral court robs ultra-nationalists of their heroes, whose presence in these countries—hiding in plain sight—functioned as an implicit justification of the wars and their brutality. Once Karadzic (currently on trial), Mladic and Hadzic are tried, the UN tribunal can close its doors, which will be a success story and precedent for the international rule of law.

Even though the arrest of the final, outstanding war crimes suspects will close one chapter of the wars of the 1990s, namely that of legal prosecution, it is only one step in a much more complex process. The hard work of “processing history,” or Geschichtsbewältigung as the Germans call it, has only begun in Serbia, where there is still no consensus that the wars perpetrated in Serbia’s name were wrong and that Serbia bears primary responsibility for them.

The Serbs have to dig deep into their national history and political culture in order to grasp how and why it was that these wars, the worst in Europe since World War II—and even genocide—could be perpetrated at their hands, and why so many Serbs supported the ultra-nationalists so uncritically. While this process of introspection and self-critique is not easy for any nation, the Central and Eastern Europeans have shown themselves particularly reluctant to take it on. Croatia, which played its own sinister role in racing to partition Bosnia and then pay back Croatian Serb separatists, is hardly less recalcitrant than Serbia.

Indeed, the papered-over atrocities of World War II on the Balkan peninsula were at the root of nationalist justifications for the wars of the 1990s. A painful coming to terms with the past, however, initiated from within Serbian society, is the only way Serbia will ever establish a competent democracy rooted in liberal political values, and the only way for it to live peaceably alongside its neighbors—hopefully, within the borders of a united Europe.