LAST week in Brussels, NATO completed its long-awaited study of NATO enlargement. This is just the latest step in building transatlantic security for the 21st century, with the United States in the lead. The security fundamentals include a growing, evolving NATO, a strong link between NATO and Russia, an active Partnership for Peace linking all the emerging democracies of the former Soviet bloc through military cooperation, and a vibrant Organization for Security and Cooperation in Europe.
Against this vision stand two backward-looking sets of critics. One set seems nostalgic for the cold war and eager to pronounce as failure Russia's painstaking effort to shed its Communist past. It demands NATO's precipitous expansion, which could drive Russia into hostile isolation - which we seek to avoid.
The second group would freeze NATO. By ruling out in advance the natural growth of the West's most important alliance, they would lock all of Europe's new democracies behind cold-war lines.
Both groups - one shouting ''expand NATO now!'' and the other ''never expand!'' - look back to the cold war's threat or the cold war's boundaries. We can do much better.
We must respect Russia's great experiment with political and economic reform. We are realistic about the challenge posed by antireformers and nationalists. But history is not fate. Realism lies in doing our best to support reform.
Equally, we must keep faith with Europe's other emerging democracies. Their democratic revolutions brought down the Berlin Wall and helped end the cold war; their free-market transformation since 1989 has astounded the world.
Some suggest that Russia is the only key to security. Echoing Neville Chamberlain at Munich, they insinuate that the other new democracies are far-away countries of which we know little and care less; that their fate must be held subject to Russian politics, as if we can secure democracy in one country by compromising its prospects in others. But history shows that the United States ignores Central and Eastern Europe at its peril. There is no security for the US - or for Western Europe and Russia - with out security at Europe's heart. The answer is to offer Europe's emerging democracies the West's institutions if their reforms continue.
Gradually and openly extending NATO membership will give the US committed new allies. NATO expansion also will buttress stability and enhance security, just as it did when NATO brought in Turkey, Greece, West Germany, and Spain.
Extending security guarantees raises real questions:
Why get involved at all? Because experience shows that the best way to prevent conflict is to build security structures carefully, in advance of problems.
Why enlarge NATO if Russia is no threat? NATO was created as more than a cold-war alliance defending against Moscow. It was and remains the great alliance of the world's democracies. It can foster stability for Europe's new democracies just as it has for Western Europe for 40 years.
Are any of the new democracies ready for NATO membership? NATO's next members will be as democratic and stable as were many earlier entrants. Let those seeking membership be allowed to test their readiness against NATO's clear standards uniformly applied.
What good is NATO if it cannot stop the Bosnian conflict? NATO is showing that force harnessed to diplomacy can be effective and will be key to implementing the peace settlement we are now actively seeking to negotiate. Many Central and East European nations regard NATO as essential to preventing future Bosnias.
As President Clinton has stressed to President Yeltsin, NATO is no threat to Russia; NATO enlargement will increase Russia's security by stabilizing democracy to Russia's west. NATO stands ready to launch a new and substantial partnership with Moscow, perhaps codified in a formal agreement - an ''Alliance with the Alliance.'' But such a partnership must not be at the expense of the other new democracies. We hope that Russia will continue moving forward in its relations with NATO. Perhaps by year's end, NATO and Russia will have agreed on a framework for their long-term relationship.
America and its allies won the cold war through realism, strength, and values. We can win the peace by holding to our principles: The West and its institutions ought to extend as far as stable democracy itself reaches. President Clinton's policy shows the way.