LONDON -- At first glance the contrast could not seem more striking: While Western Europe's countries next month will open negotiations to surrender more of their state powers to the European Community, a host of small, nearly forgotten ethnic groups to the east -- Serbs, Macedonians, Lithuanians Armenians and others -- are seeking to form new countries and gain some of those state powers.

The target of these seemingly conflicting movements is one of the world's most enduring institutions, the modern nation-state.

Pulled from above and torn from below, the nation-state is going through a period of stress and strain that analysts say could not only alter the political map of the world but also transform the notions of sovereignty and nationhood.

"This is going to be one of the most important issues of our time," said William Wallace, professor of international relations at St. Antony's College at Oxford University. "Many of us thought the nation-state was finished after World War II, but it underwent a revival. Now, however, it is buckling."

The search for a new global order to replace the bipolar world of East versus West is leading to larger roles for supranational organizations such as the EC, the Conference on Security and Cooperation in Europe and even that old standby, the United Nations. All are moving into areas that were once the sole domain of individual countries: economics, defense and human rights. Issues such as the environment, terrorism and drug trafficking are demanding multinational action.

Such issues are the stuff of international conferences in plush meeting halls. But not so far away, in more rugged settings, states are being pressed in different, unpredictable and potentially violent ways by ethnic, religious or political groups seeking self-determination in the form of autonomous rights within existing states, their own separate countries or reunification with homelands across their borders.

Analysts say these centrifugal forces largely stem from the same sources: the thawing of the Cold War and the subsequent release of conflicting nationalisms after decades in the Soviet deep freeze, the "globalization" of the world economy and the search for ways to protect distinct cultures and human rights.

The results are visible not just in the collapse of the Soviet empire, but in seemingly more stable and established nations. The future of Canada is in question because of conflicts between the English-speaking majority and the French minority. In Britain, Margaret Thatcher's government is threatened with collapse not over the country's flagging economy, but because of deep divisions over how much of its cherished sovereignty Britain should give up to the European Community.

All of this may seem like a major upheaval for a long established institution. But in fact, most of the nation-states we know today are jury-rigged contraptions that owe their existence to the 20th-century collapse of the Ottoman, Hapsburg, British and French empires and derive most of their powers from distinctly 19th-century models. More than 90 of the U.N. General Assembly's 159 member states were born after World War II. Analysts say the problems of virtually every world trouble spot can be traced in part to defects in the nature of those states.

The borders for most of Africa's 50-odd states were drawn up by the great powers at the Berlin Conference in 1884 with maximum concern for the balance of power in Europe and little or none for the ethnic, linguistic or cultural affiliations of Africans. When the great empires withdrew from the continent four generations later, they left behind cardboard countries without the glue of nationhood. Many of the civil wars that ensued -- in Nigeria, Sudan, Ethiopia, Angola and Mozambique, among others -- were a direct result.

Even those states that avoided outright civil war have been plagued by a lack of national identity. The authority of African rulers often ends at the boundaries of their capital cities. In the countryside, where the majority of Africans live, people identify with their family, tribe or region. There are Kikuyus, Luos, Kalenjins and two dozen other ethnic groups in Kenya -- but few outside Nairobi who call themselves Kenyans.

In South Africa, people may call themselves South Africans but hold dramatically different definitions of what they mean. The white-ruled government celebrates the Afrikaner triumph at the Battle of Blood River as a national holiday, but ignores Soweto Day, which is honored by most blacks. Blacks and whites fly different flags and sing different national anthems.

The borders of most of the modern Middle East are equally artificial, derived from the division of spoils between the French and British after the Ottoman Empire crumbled during World War I. Iraq's search for a viable outlet to the Persian Gulf, Syria's designs on Lebanon and Israel's refusal to relinquish the occupied West Bank all have their origins partly in the lines drawn and redrawn by the two imperial powers.

In fact, historians say, the nation-state itself is often a contradiction in terms. States are legalistic, governmental entities that wield power; nations are vaguer: groups of substantial numbers of people who share a culture, language, religion, history, or all four. Some countries -- the United States, Canada, Switzerland, Belgium, Sri Lanka -- are not unitary nations at all but "multinational" states. And some nations -- Kurds, Palestinians, Armenians, Basques, Crees -- have no state.

There are few genuine "nation-states" where the two concepts come neatly together. Japan is one. Britain, with its unruly mixture of Scots, Welsh and English, and its twilight war zone in Northern Ireland, decidedly is not.

Lenin tacitly accepted these definitions when he called the czarist empire a "prison of nations." But the 15 supposedly voluntary members of the Union of Soviet Socialist Republics and their neighbors in Eastern Europe contend the Communists substituted one kind of prison for another. From their perspective, the collapse of the Soviet Union actually would represent a triumph of the nation-state, the long overdue death of the world's last empire.

But the tumultuous return of East European nationalisms with their ominous undertones of fascism and anti-Semitism transpired while many Western Europeans were looking in the opposite direction and has spurred some to redouble their efforts to press ahead with greater European economic and political union.

"We have concluded from that very cacophony we are hearing that there is no choice but to deepen the European Community as an alternative to the Balkanization of Europe," said Thomas Kielinger, editor of the Rheinischer Merkur, the prominent German political weekly.

Most European Community members have followed Germany's lead, with the notable exception of Britain. Margaret Thatcher sees further European economic and political union as a threat to state sovereignty.

Sovereignty means controlling one's own national destiny, Thatcher says. Practically put, most analysts define it as the right to print money and make war.

But many analysts contend national sovereignty in both areas -- economics and defense -- has long been eroded. The last time Germany's Bundesbank raised interest rates, the Bank of England followed suit within an hour. The nervous systems of the major national economies have become linked like Siamese twins. If one country raises taxes or fails to provide adequate schools or infrastructure, firms are likely to pick up and move elsewhere. And when Washington or Tokyo gets a cold, London, Paris and Frankfurt feel the chill.

Similarly, defense has become a collective concern. "Defense is the most sensitive area when it comes to losing sovereignty, but the dynamic is already there," said Francois Heisbourg, director of the London-based International Institute for Strategic Studies. "After all, the NATO countries, especially West Germany, surrendered substantial powers in the face of an external threat. If a body of nations like the European Community transfers sovereignty from the national to the supranational in the field of currency or foreign policy, it becomes inevitable that defense will follow."

Ultimately, the objections of Thatcher and her supporters are not only about sovereignty but about something even more elusive: national identity. Many Britons see themselves as different from other Europeans and fear their distinctiveness would be lost in a federal Europe that was somehow less democratic and more centrist.

"The argument is not whether we are going to be part of Europe, the argument is over what kind of Europe it will be," said a senior aide to Thatcher. He recalled a meeting of European heads of state in Madrid last year where an official of another country told him Britain's problem was that it was "proud of its past" while others in the European Community were "trying in some way to escape theirs. I don't think we in Britain have any feeling of wanting to get away from the past."

The chauvinism that lurks behind those remarks is another tangible trend in the new Europe. For some Britons or Frenchmen or Germans, national identity excludes those who are brown-skinned or Moslem. Nativist movements are on the rise in all of these countries, in part as a reaction to the tumultuous changes lowering their borders and threatening their own sense of identity. A British tabloid's recent "Up Yours, Delors" campaign against the president of the European Commission, Jacques Delors, was designed to sell newspapers by tapping a deep current of resentment and fear about foreigners.

"All of this rapid change and social unity may be splendid for some of us but not so splendid for our working classes, who don't get all the privileges," said Oxford's Wallace. "We may see a transnational Euro-elite who have a whole different set of experiences and expectations than working people in Belfast or Munich.

"Nationhood for many people solves the question of identity. It tells us who we are and who we like and who we don't like. At a time when someone may be working for a Japanese company and living next door to Bangladeshis, we're facing a real identity crisis about what it means to be British."

European visionaries once spoke of a United States of Europe where all borders and national governments would melt away, leaving a collection of regions and local identities. That now seems fantasy. Frenchmen will continue to be Frenchmen, Germans will be Germans. But the hope is that they will also call themselves Europeans.

"Will nation-states fade away?" Heisbourg asked. "I don't think so. Will state sovereignty fade? My answer is yes."