In purely military terms, the force of 430 aircraft and cruise missiles the alliance has amassed against President Slobodan Milosevic over Kosovo is more than enough to overwhelm the Yugoslav defences, including its still-redoubtable ground-to-air missile systems.
But even the threat of using that firepower constitutes a watershed for the alliance. For the first time, it is going to war inside the borders of a sovereign country, against the express will of the government of that country. The closest parallel is the despatch of United Nations troops to Somalia in 1992, but in that case the country's central government no longer functioned. No less open to argument is whether Nato is acting on the authority of the UN - an issue that will keep experts in international law busy for years.
After no little hesitation, the 16 member countries appear to have unanimously convinced themselves they have that authority, both on imperative humanitarian grounds and the need to preserve international security in the Balkans. But the fact remains that Nato does not have and, given the certainty of Russian and Chinese vetoes, never will have the explicit Security Council backing it enjoyed when it attacked the Bosnian Serbs in 1995.
Thus the Kosovo crisis of 1998 already marks a watershed in the history of Nato.
Next April in Washington, the organisation is staging a jamboree - part business, part celebration - to mark the 50th anniversary of what is perhaps the most successful military alliance in modern history. But the very triumph raises the question which has launched 1,000 conferences: precisely what is Nato for, now the Cold War is over?
Answering it is the business part of the gathering, as it seeks a new "strategic concept" to replace the present one, dating back to 1990 when the Soviet Union was still the adversary.
If Nato, preferably without resorting to air strikes, can end the fighting and set in motion the return of refugees and negotiations for a lasting political solution, then its role will be clear. It will be the grouping responsible for ensuring peace and security in Europe, and spreading the gospel of Western democracy around the globe. That is exactly as the US would like it - but several European countries, notably France, are more dubious.
If massive air assaults instead merely add to instability in the region, the warning by the Russian Foreign Minister, Igor Ivanov, of "international chaos" might be borne out.
Nato troops would inevitably be stationed en masse on the soil of a hostile country. The east/west divide in Europe would be accentuated and other countries may be tempted to claim the right to use force beyond their borders. Nato's own authority would be hugely weakened and its future thrown into question.
Among the doubters must now be counted Dr Henry Kissinger. Military action was all every well, he told a conference in Prague yesterday, but to what end? "I don't see an end today in the deployment of B-52s. It is beyond my comprehension what they are supposed to do in an ethnic conflict at the edge of the Balkans."Reuse content