The images of the first breaches of the Berlin Wall, with joyful East Berliners pouring through into the West, are forever associated with the end of the Cold War. Presidents Bush and Gorbachev declared the superpower confrontation over when they met off Malta a few weeks later. Although for a while some suspicious souls thought the Soviet Union might stage a comeback as a great and aggressive power, it soon became apparent that it could no longer play this role. In August 1991 the old hardliners could not even manage a decent coup. Now it is only the nuclear arsenal that lingers as a reminder of the Soviet Union's formidable past, while Russia's regular forces, hit by manpower shortages and a lack of resources, are but a shadow of the old Red Army.

The revolutions of 1989 appeared as the death of an ideology. Throughout Eastern Europe it had become apparent few were convinced that state socialism remained a sensible way to organise an advanced industrial economy, or that the communist party deserved to rule unchallenged. The system had lost so much legitimacy, was so rotten inside, that once it could no longer be sustained by Russian arms it simply crumbled. After more than four decades of communist rule, the only ideology that now had any credibility in the East was capitalism.

Yet it was not only the Cold War that concluded in 1989. It also marked the end of the European empires. The second World War weakened the grip of the imperial powers on their overseas possessions. Encouraged by the United Nations, and starting with Britain's withdrawal from India, the second half of the century saw a great surge in decolonisation, to the point where membership of the United Nations more than tripled as numerous new states arrived on the international scene.

As Moscow and Washington vied to persuade these newly independent states to join their respective blocs, the Third World suddenly began to provide some of the major Cold War flashpoints, most notably in east Asia and the Middle East, but also in Africa. When the last of the west European empires - the Portuguese - suddenly collapsed in 1974, once again East and West were at loggerheads over the future of Angola.

The west European empires were maritime. By contrast, the Soviet empire was created through land conquest. The east European countries were the most recent entrants and so they were the first to go. Once it became apparent that Moscow was reluctant to use force to hold on to territory, then the Baltic states of Lithuania, Latvia and Estonia, taken by Stalin at the start of the second World War, agitated to leave. At the end of 1991 the Soviet Union just fell apart, with Russia no longer prepared to subsidise unproductive republics or fight to hold on to them, and 15 states stood where there had previously been just one.

The process did not stop. Russian forces are now fighting in Chechnya because of a determination to stop a further crumbling at the borders. Chechnya illustrates a problem with the collapse of empires and multinational states. Once articulate groups start demanding independence in the name of self-determination, where does the process stop?

As any entity that can trace its roots back well into history decides it wants sovereignty, then a new state can split again and there seems to be no logical place for the fragmentation to stop. It is not just the Soviet Union that has come apart over the last 10 years. Czechoslovakia split into two and, with terrible violence, Yugoslavia split into five, with now Montenegro as well as Kosovo straining to get away.

The Cold War had been extraordinarily dangerous because it carried the risk of a nuclear confrontation, but at the same time it also appeared remarkably durable. Because the battle lines were so clearly drawn and unambiguous, coexistence between the two blocs proved surprisingly easy. If the Soviet side had not imploded then the Cold War relationship could have continued for some time on the same basis of confrontation moderated by intensive communication and occasional co-operation.

Diplomats now look back with nostalgia at a time when so much seemed certain and settled, forgetting perhaps the price paid by those whose aspirations were crushed by the dead hand of a repressive state socialism or the real anxieties generated by the thought that this apparently indefinite standoff could quite suddenly come to an end with a nuclear calamity.

Thankfully it was not an explosion between the blocs, but the Eastern implosion that brought the Cold War to an end. Yet the implosion turned Europe from an oasis of stability in an unstable world into one of the more turbulent of continents. It was as if a long-locked cupboard, full of old worn nationalisms and prejudices had suddenly burst open.

Problems that once seemed quintessentially "Third World" became common in Europe, especially to the south-east towards the Balkans and the Caucuses, with violence endemic and routine, criminal groups rushing in as incoherent states and weak regulatory structures failed to cope, and economic distress.

WEST European states, having been quite happy for Moscow to cope with some of the least productive and more awkward parts of the continent, suddenly found a number of states released from the demands of their imperial and ideological shackles, looking eagerly in their direction. Having spent decades getting rid of empires they found themselves, in effect, offered a new one. There were eager applicants for the core Western institutions of NATO and the European Union, a desire for guidance in Western ways and an even stronger desire for finance to help ease the unexpected transition from socialism to capitalism.

The Western states recognised their responsibility, but with misgivings as they began to sense dangers in opening up to cheap exports or population flows, or getting involved in vicious local squabbles. The response was therefore mixed - the states best equipped to engage with the West politically and economically made stunning progress over the 1990s, with not only East Germany reunited with the West, but also Poland, Hungary and the Czech Republic even joining NATO, much to the chagrin of Russia.

States that could not quite make the transition, including many of those from the former Soviet Union, floundered, looking for bailouts to help them cope with the shock of the collapse of currencies and old industries.

The reluctance of Western countries to intervene in post-communist conflicts left them spectators to upheavals in and around the periphery of Russia. Nonetheless, despite their best efforts, they could not stay out of the wars of the former Yugoslavia, and ended up this year taking on Serbia over Kosovo. As a result of this intervention the United States and Western Europe now find themselves obliged to develop effective economic and political structures for the whole of the Balkans.

Ten years after the end of the Cold War the problems in Europe result as much from attempts to fill the gap left by a retreating empire as by a defeated ideology.

Lawrence Freedman is professor of war studies at King's College, London.