Today marks the twentieth anniversary of the start of the 1999 U.S./NATO bombing campaign of what was still Yugoslavia. It was a watershed moment in U.S. foreign policy in that it was the first time that the Atlantic alliance had waged a war at the insistence of the United States, it was the first in a series of wars that the U.S. waged over the last two decades that was completely illegal under international law, and it was an aggressive U.S. military campaign waged against another state without even token Congressional approval. Many of the worst features of early 21st-century U.S. foreign policy were already on display in the Kosovo war, which has since been treated as a “good” intervention because it eventually forced Serb forces to withdraw from part of their own country. President Clinton got away with waging a blatantly illegal war more than two months, NATO was transformed from a nominally defensive alliance to one willing to attack its neighbors, and Western governments launched the first of several attacks on sovereign states without authorization. Whenever interventionists have wanted the U.S. to strike at another government, they have understandably cited Kosovo as proof that Washington can ignore the U.N. and the requirements of the Charter.
The Kosovo war paved the way for the eventual recognition of Kosovo independence over the objections of Serbia, and the illegal military intervention in Yugoslavia’s affairs provided a ready-made precedent for other states to imitate. The August 2008 war between Russia and Georgia was partly the result of the war and the later recognition of Kosovo, and the sharp deterioration of U.S.-Russian relations in the 2000s began with that war. Recognizing Kosovo’s independence without Serbian consent created the excuse for Russia to recognize the independence of Abkhazia and South Ossetia after the August 2008 war, and they took full advantage of it. The claim that the U.S. respects and upholds international law has never fully recovered from the decision to attack another government over an internal conflict. In the years that followed the U.S./NATO intervention, the war was excused as “illegal but legitimate,” but subsequent interventions have shown us that there can never be a legitimate intervention that tramples on international law. If the international “rules-based order” is under strain today, that is happening in part because the U.S. and its allies chose to run roughshod over the U.N. Charter and wage an aggressive war against another state that posed no threat to any of them.