For much of its 50-year existence, the question of when and how the North Atlantic Treaty Organization could or would use force was never in dispute. As a military alliance formed to provide for the collective defense of its members, NATO sought to deter and, if necessary, defend against an attack by the Soviet Union and its Warsaw Pact allies on the territory of one or more of its members. Only in the 1990s did the question of when, where, and how to use force for purposes other than collective defense emerge. NATO’s involvement in the Balkans—first in Bosnia, now in Kosovo—suggests that while the allies may remain divided in theory on issues relating to the use of force, they have in practice arrived at a consensus.
NATO’s Kosovo war provides answers to three questions that have stymied the allies during the 1990s. First, under what circumstances should NATO threaten or use force?