The Cold War was said to have ended with the fall of the Berlin wall, but the withdrawal of American, Allied and Russian troops from Berlin marks its real end, removing all foreign forces from Central Europe. President Clinton's speech at the Brandenburg Gate next Tuesday will end a 50-year American engagement in Central Europe that had no precedent, and which, one must surely hope, will require no sequel.
The American and Allied units remaining in Germany are no longer there for Cold War reasons but as part of a common effort, in which Germany is a full partner, to institutionalize a new collective security against threats that can only be identified in abstractions: disorder, extremism, nationalism, national breakdown.
No tangible security threat to North America or to Central and Western Europe -- or to Russia -- now exists. Yet the perception of a generalized insecurity is much stronger today than it was when both Allies and the Soviet Union lived by mutual nuclear threat, with their societies organized for war.
There are both good and bad reasons for this sense of insecurity.
The weakening or disintegration of certain social structures in the former communist countries, and the economic upheaval they experience, nourish extremist reactions of the kind that have ravaged the former Yugoslavia and were commonplace, and lethal, during the interwar years. Radicalism in the Islamic world is perceived as a threat, at least indirectly, not only because of its practice of terrorism but because it generates refugee flows toward the Western countries. The same is true of the breakdown of African states.
The lack of an explanation for all of this also causes insecurity, and this has perhaps the greater influence on Western policy thinking. A search has been on for some time to find a theory, an idea, that will make sense of these challenges, and thereby imply a solution, or at least the possibility of a sweeping solution. We miss Marxism, the theory that explained everything. The anti-communists may miss it even more than the Marxists. It gave a political meaning to their existence as well as to that of the communists, providing both with their policy agendas.
The search for a unifying theory of foreign policy has been going in the U.S. since the Cold War ended. Mr. Clinton started out by appropriating the Bush administration's argument that since communism had collapsed, the world now was taking up democracy and the U.S. had only to lend its cooperation. This proved neither true nor useful in the situations the U.S. has found itself in: Somalia, Bosnia, Haiti, North Korea and Rwanda.
Francis Fukuyama's theory about the end of history and Samuel Huntington's proposal of coming wars between civilizations found an audience among policy makers because they seem to offer the missing general explanation.
However, the true unifying theme is that there is no theme. There is no single threat today, hence no single answer. There are discrete problems.
There is the problem of re-establishing Russia in a responsible role in the international system. There is the challenge of assuring the security of the former communist-controlled states in central and eastern Europe without isolating Russia.
There is the problem of national development and international aggression in the Soviet successor states and the Balkans, where people are driven by nationalist emotions disproportionate their social and economic capacity to function as modern nations.
There are the problems produced by economic and demographic pressures in the nations adjacent to the industrial nations, provoking migratory flows as well as political conflicts.
There is Africa, where Western national interests may not be engaged, but human solidarity is affronted by the collapse of social structures and by terrifying ethno-tribal and communal conflicts.
There are competitive tensions among the advanced nations themselves, which have political consequences. Economic rivalry between Japan and the U.S. has already provoked demagogic reactions that go as far as the forecast of war.
But none of this possesses a common theme. This is history as it usually happens. The important thing today is not to be panicked by the loss of a unifying theme in international relations. The challenge is to take problems for what they are.
The Cold War had a theme; it was an exceptional period; we are well out of it. We now are back to the usual disorder of history. As Mr. Clinton and his associates have discovered, living with complexity is very hard. But it is better than dealing with the lethal simplifications that dominated international relations between 1918 and 1989.
William Pfaff is a syndicated columnist.