Four years after it was "liberated" by a NATO bombing campaign, Kosovo has deteriorated into a hotbed of organized crime, anti-Serb violence and al-Qaeda sympathizers, say security officials and Balkan experts. Though nominally still under UN control, the southern province of Serbia is today dominated by a triumvirate of Albanian paramilitaries, mafiosi and terrorists. They control a host of smuggling operations and are implementing what many observers call their own brutal ethnic cleansing of minority groups, such as Serbs, Roma and Jews. In recent weeks, UN officials ordered the construction of a fortified concrete barrier around the UN compound on...