After Radovan Karadzic's capture earlier this week, we asked Derek Chollet--who worked with Richard Holbrooke on a book about the Dayton Accords and is also a senior fellow at the Center for a New American Security and co-author of America Between the Wars--to assess the fallout. Here are his thoughts:

Seeing the pictures of the former Bosnian Serb leader Radovan Karadzic, with the mane of white hair and enormous beard, one could easily mistake him for some over-the-hill hippie, not the "Himmler of his generation," as a top American diplomat once described him. What's remarkable is how ordinary his life had become, and how public he remained--treating patients in alternative medicines, publishing poetry, speaking at conferences, all under an alias. For years most Balkan watchers believed that Karadzic was hidden in some remote monastery in the hills of his native Montenegro, while it was his henchman, Ratko Mladic, who was supposedly hiding in downtown Belgrade. Earlier this year, I met with several senior Serbian government officials who promised that Karadzic was "somewhere in the hills," while he in fact he was living right under their noses.

Karadzic's capture is a major event for the Balkans--seeing him behind bars, and watching his upcoming trial unfold at The Hague, will be an important step in healing the wounds created by the Bosnia War. For the relatives and loved ones of the thousands who were massacred in Srebrenica in July 1995 (when Karadzic issued the stunning order to "kill all the men"), or for those living in Sarajevo besieged by Serb artillery and snipers while Karadzic watched from the mountains, this will be justice delivered. For the Serbs throughout the former Yugoslavia, in Bosnia and Serbia, it will be a moment to confront a difficult and painful past. For the Serbian government in Belgrade, which aspires to be closer to Europe, this is an important step in getting it there (but the process cannot be complete until Mladic is behind bars as well).

This is also good news for the United States. It is easy to forget that in the months after the Dayton accords brought peace to Bosnia, American-led NATO troops refused to arrest Karadzic for fear of sparking violence--even as he drove through NATO checkpoints. But since then, U.S. diplomats made Karadzic's capture a major priority in America's relations with Serbia, so they too deserve credit for keeping up the heat.

Finally, the coincidence of Karadzic's arrest with the most hyped event in U.S.-European relations in quite some time--Barack Obama's visit to Europe this week--reminds us of the lessons of the Balkan Wars of the 1990s. Then, America and Europe failed because we did not take action against the likes of Karadzic until the bloodshed had spun out of control. We did not work together, and it almost brought down the relationship just years after the Cold War victory. Eventually the U.S. did take charge, using tough diplomacy and military force to end the Bosnia war, sparking the chain of events that sent Karadzic into his hirsute glory and a new career in alternative medicine, and now to jail. The lesson for today is one that I believe Obama understands: that American power can be a force for good--and that not using it often gives a free pass to evil.

--Derek Chollet