The United States and European Union need to support the newly independent republic of Kosovo. The situation is politically tricky but there are good practical reasons for doing so.
The essential question is not can Kosovo become independent? Instead the question must be, what other options are there. The conflict and war crimes that occurred in Kosovo killed any sense of kinship Kosovar Albanians had with Serbia. Additionally eight years of forced separation by the 15,000 international troops that make up NATO's Kosovo Force make reintegration to Serbia unlikely.
In order for Kosovo to return to Serbian control the Serbian governement would have to reenter the region and assert sovereignty. Sovereignty is the monopolization of legitimate force within a geographical region. I can see no conditions where the Serbian assertion of force to legitimize political control is going to be well or peacefully accepted. Allowing it to happen would be inviting further violence in a region that has a history of ethnic and religious tension dating back centuries.
When you consider these facts I feel that it is clear that independence in Kosovo is in the best interests of both parties. However the resistance to Kosovar independence is not just about Kosovo. The countries in Europe withholding their support of independence are Russia, Cyprus, Greece, Slovakia, Spain, Bulgaria, Romania and obviously Serbia.
Russia, Cyprus, Romania and Spain are hesitant or outright refusing to recognize independence in Kosovo because they have ongoing problems with nationalist secessionist movements in their own country (Chechnya, Cypriot Turks, Hungarian and Basque respectively). Greece is tightly bound into the problems in Cyprus.
Bulgaria is withholding support because they just signed a deal with Russia to build an oil pipeline and do not wish to anger a country with a history of turning off the flow of energy to Russia.
Slovakia is in the awkward position of being a main supply route for NATO equipment into Kosovo. Additionally Slovakia has national elections scheduled for 21 April in which their support of NATO is already an issue that threatens to unseat the current government.
With all of these facts considered there are several steps that can be taken to ensure that the situation comes to a positive outcome for all parties. Primarily western governments need to provide justification based on human rights and the unique historical conditions. Secondly they need to continue to ensure the security situation which includes protection for Serbia as well as protection of Serbians living in Kosovo.
The primary justification for the recognition of Kosovo needs to be the promotion of human rights and the prevention of the human rights abuses that are bound to occur on both sides of the conflict if Serbia reasserts their sovereignty in Kosovo. This is something well within the capacity of the NATO force already in place.
Additionally the EU and U.S. should work with the UN, Serbia and Kosovo to provides money and assistance with the voluntary resettlement of people to either side of the border. This is a show of good faith and would be a trust building exercise for both countries. Additionally it is a gesture that extends the principles of self determination and personal freedom to the lowest levels.
Most importantly the U.S. and EU must emphasize that support of Kosovo is not a precedent for other nationalist separatist movements around the world. This needs to be stated vocally and likely included in any Security Council resolution in order to gain the support of Russia.
Kosovo is a special case for several reasons. First there are unique historical conditions of conflict and separation in the past eight years. Second Kosovo has formed an orderly, civil government that has seats reserved in their assembly for ethnic Serbians and another block of seats for other ethnic minorities. Third they have trained a police force under international supervision to keep the peace while ensuring that they remain professional in respecting minority rights. Additionally the two years of talks that have ended in frustration should be shown as clear signs that a reunified state is unlikely.
To my knowledge no other separatist group can claim this set of conditions. With that considered hopefully support can be gained by enough key players that the situation is peacefully and prosperously resolved.