Now we know what the mark of Cain must have looked like. It was a tuft of black atop the wild white hair of a wandering old killer who called himself a healer. The benign disguise of Radovan Karadžic should have surprised nobody. His cunning in the concealment of his malignity was abundantly proven in the years when he was the architect of the Bosnian genocide. He fooled the leaders of the West--Clinton, Christopher, Lake, Vance, Carter, Carrington, Owen, Rifkind, Hurd, and of course Boutros Ghali and Annan--long enough to destroy more than 200,000 men, women, and children. They met with Cain, they shook his hand, they heard him out, they gave him what he needed most for his evil--time; and until they stopped him, they did not stop him.

It was fitting, in a way, that Karadžic eluded capture for so long: the world in which he perpetrated his horrors--a hot country, a cold world--was never especially outraged by him. The Americans finally acted against him when CNN and the bizarre terms of the U.N. deployment in Bosnia made it impossible for them not to act; and the Serbs finally arrested him when his arrest became a condition of Serbia's admittance into the European Union. (For ten years, his mark notwithstanding, Cain enjoyed the protection of his community and his church.) The denouement of the Balkan disaster has always been a spectacle of the right thing ingloriously done. It was not high principle that brought Karadžic down--not then, not now. For this reason, the joy that we feel at his apprehension is rather a shadowed joy. His indictment and his conviction before an international tribunal will certainly stand as a milestone in the campaign against genocide, and the fiend deserves whatever awaits him; but somehow it is too late, and too bitter, to call this justice. Justice, strictly understood, must come before genocide, not after genocide.

Cain, of course, conceded that it was his brother that he murdered. But it was Radovan Karadžic's special contribution to the Serbian crime to repudiate the possibility of brotherhood across national, cultural, religious, and even biological lines. He provided death's theory. He, the poet and the psychiatrist, was a master de-humanizer. It is said that Karadžic even devised the phrase "ethnic cleansing." In 1991, he proclaimed that the Muslim community of Bosnia would "disappear from the face of the earth" and foresaw "the beginning of the end of their existence as a nation." He justified the sadism of the siege of Sarajevo this way: "Never hold a snake by the tail, but by the neck." In 1995, he gave this order to the Bosnian Serb forces under the command of Ratko Mladic, who is still sipping tea somewhere in Serbia: "By planned and well-thought-out combat operations, create an unbearable situation of total insecurity with no hope of further survival or life for the inhabitants of Srebrenica and Zepa." The obscenity that followed is well-known. "Srebrenica" is now one of those words, like "Guernica" and "Lidice," that are Western scars. To see it again in the newspapers last week was to have one's sense of darkness refreshed.

And not a moment too soon. For the capture of Radovan Karadžic is an event with implications not only about the past. Here is Ben Kiernan, in his fine history of genocide: "A year after the publication of the Serbian Memorandum [the xenophobic manifesto of Serbian intellectuals that provided the ideological foundations for the Bosnian genocide], in October 1987, a group from the Darfur region of western Sudan, calling itself the Committee of the Arab Gathering, sent a similar letter of ethnic complaint to the Sudanese prime minister in Khartoum." Karadžic, in other words, is a man of his time. In this era of genocide, there is nothing anachronistic about him. Even as he was hunted down for his indictment for crimes against humanity, the International Criminal Court at the Hague was indicting Omar Al Bashir, the president of Sudan, on similar charges for the atrocities in Darfur. Two days after Karadžic was finally apprehended, his African counterpart--Cain's other brother, the one not unlike him--embarked on a triumphal tour of his country, dancing jigs on the roofs of trucks before smiling crowds. The crime, the philosophy, and the defiance are the same. So is the challenge to us, and to what we profess to believe.

"Will we give meaning to the words 'never again' in Darfur?" Barack Obama asked, as he ticked off the ills of the world in his speech in Berlin. Uh-huh. Sure we will. Yes, we can. But only if we are willing to use our power--not our soft power, but our hard power. The use of military force by the United States and NATO in the Balkans--belatedly in Bosnia but promptly in Kosovo--remains the only model for an effective response to the extermination of peoples.

Whatever one thinks of the war in Iraq, it is impossible to deny that it has had the effect of delegitimating "humanitarian intervention" for a new generation. This new diffidence must be resisted. It is what the mass murderers and the mass rapists are counting on. You cannot be against the genocide in Darfur and against the use of force to end it. Otherwise your opposition to the atrocity is purely gestural, and merely a display of your admiring sense of yourself. It makes no sense to be opposed to a problem and to its solution. So it is good that the butcher of Bosnia has met his day; but the real way to capture Radovan Karadžic is to capture Omar Al Bashir.

By The Editors