The previous arrangements for defense of western Europe are obsolete. There is some clamor to disband NATO altogether, but that is unlikely to happen.

US European Command says the Soviets can make all of their arms control reductions and still generate 60 divisions west of the Urals, with more available from the Far East. That is too much of a threat to ignore, and new threats are emerging. By the turn of the century, eight nations that were not part of the old Warsaw Pact will be able to target western Europe with ballistic missiles.

Sooner or later, NATO has to stop ducking the "out-of-area" question and address the problem of military aggression that challenges Allied interests but that occurs outside of Alliance territory.

Europe seethes with uncertainty. The former Soviet client states are struggling to establish direction and identity. A RAND Corp. study for the Pentagon nominates Poland, Czechoslovakia, and Hungary to be a permanent buffer zone between western Europe and the Soviet Union. As RAND acknowledges, however, those nations may have a different destiny in mind.

The civil war in Yugoslavia has awakened memories of the internecine turmoil that swept Europe regularly before the cold war imposed a precarious stability on the continent 45 years ago.

Germany, reunified and potentially the dominant power in Europe, makes its neighbors nervous. There is also speculation that the Germans, long disposed toward closer ties with the East, may eventually throw in with the Soviet Union. The permutations feed on each other. For example, as Alexander Haig warns, an obsession to constrain Germany could itself lead to conflict.

Against this swirling backdrop and with no assurance of what the future holds, NATO is plunging ahead with a top-to-bottom revision of strategy and objectives. Its new approach assumes a much smaller force defending a considerably larger territory in which battle lines cannot be drawn in advance.

NATO forces should be well equipped. The US, Germany, and the Netherlands are donating modern tanks, armored vehicles, and artillery to Allies who will then satisfy arms treaty requirements by destroying older equipment. NATO's inventory of combat aircraft and helicopters is already below the treaty ceiling by a wide margin.

(The Soviets, who are provisioned massively, get less benefit from permissible transfer of equipment. According to the US Arms Control and Disarmament Agency, the Soviets can keep only 35 percent of what they had in Europe in 1988.)

By 1995, US deployments in Europe will consist of two Army divisions three air wings, and a maritime presence in the Mediterranean. The Europeans are organizing a Rapid Reaction Corps, perhaps four divisions to be led by the British. It would be backed up by in- place defense forces composed of active and reserve troops for whom readiness standards would be relaxed. The ultimate backup is mobilization, relying heavily on reinforcements from the United States.

Some schemers are more ambitious in what they seek to achieve from the restructuring. They would like to build the "European pillar" of allied defense around the West European Union or some other alternative organization, thereby undercutting US influence in the Atlantic alliance.

The prevailing view, so far at least, is that the security of Europe should be entrusted to NATO, and that for its own benefit and the good of the alliance, the United States must be involved. As Henry Kissinger observes, "without a clear American role, the psychological map of Europe as well as of Atlantic relations would be radically transformed." No proposal heard so far provides for a credible defense of Europe without America participation.

Geography and circumstance make Europe a crossroads of world events. Both world wars began there, The superpower confrontation played out most intensely there. The world's worst fears and greatest hopes still hang on what happens in Europe. Europe is vulnerable or unstable it will almost surely drift into trouble and the trouble will spread.

Planning on the rebound is not usually a good idea, but the changes of the past two years have been of such magnitude that it made no sense for NATO to wait longer to revise its strategy. Later, it may be necessary to adjust the adjustments.

Concern about European security was not some phase the West went through and can now regard as finished. It is a continuing problem and one we cannot escape.