NAIROBI, MAY 30 -- From Angola to Ethiopia this week, the end of the Cold War is transforming the political landscape of Africa at a breathtaking pace.

What a difference a decade can make. Just 10 years ago, competition between the superpowers was a preeminent force shaping political events and economic development in Africa.

The Soviet Union was busy supplying billions of dollars in aid to nominally Marxist client states such as Ethiopia and Angola in pursuit of its dream of international communism, while more than 50,000 Cuban troops were stationed there to support shaky regimes against insurgencies.

The United States, for its part, was funneling hundreds of millions of dollars in military and economic aid to African countries it perceived as vital to protecting American interests against Soviet and radical Arab threats -- Sudan, Liberia, Zaire and Somalia among them.

The roll call of African events in 1991 describes a different political landscape.

The Soviets are preaching the virtues of peace in the Third World and establishing contact with the once reviled state of South Africa.

The last contingent of Cuban proxy troops has packed up and flown home to Havana, as part of an Angolan peace accord that is expected to be signed Friday in Lisbon.

And the United States is playing the unlikely role of a political traffic cop in Ethiopia, ushering to power a rural insurgency that once idolized the example of Joseph Stalin.

What in the world is going on in Africa?

"I see a number of factors, not least a growing demand for political pluralism and democratization," said Richard Joseph, a fellow at the Carter Center of Emory University in Atlanta, which mediated Ethiopian peace discussions in the past.

"But there is also the geopolitical aspect. . . . We are living in a unipolar world. The bipolarities of the past have ended and the U.S. has emerged as the lead player. Whether this is good or bad remains to be seen, but it is clear that it has become a critical factor in Africa."

U.S. mediation of Ethiopia's civil war, which culminated in Tuesday's rebel capture of Addis Ababa, represents the latest in a number of remarkable events in Africa that, although unrelated directly, are resulting in a redrawing of the continent's political map.

The end of superpower contention, the drop-off in foreign military aid that has weakened longtime dictatorships, and popular pressures for civil liberties and more accountable governments have all played a role in these changes.

Like a pressure cooker relieved of its top, many of Africa's ethnic tensions and political and regional struggles -- some up to 30 years old -- are exploding.

The end of the Cold War "has meant that factions and governments in Africa cannot count on the consistent support of anybody, no matter what," said Claude Ake, a fellow at the Institute for African Studies at Columbia University in New York who has written extensively on democracy and political change in Africa.

"This has not only undermined people in authority, but it has given confidence to people fighting that authority. . . . Africa is entering a period of fluidity that may last some time."

Many of the recent events in Africa are devastating and still unresolved. Starved of American aid, Liberia collapsed into war last year and is still divided along battle lines.

Finally spurned by the United States, the Somali regime of Mohamed Siad Barre fell apart and the nation is still in the throes of anarchy and war.

Other long pent-up pressures are leading to new borders and even new nations founded along ethnic and regional lines. Northern Somali rebels, for example, have broken with their brethren in the south and announced the formation of the nation of Northern Somaliland.

On Wednesday, in the northern Ethiopian province of Eritrea, victorious rebels proclaimed a provisional government for the region, separate from the control of Addis Ababa. The Eritreans do not hide their desire for secession.

"It is quite likely there will be more signs of disintegration," said Ake, who explained that "such pluralism, which should have expressed itself long ago in Africa, is finally doing so."

Still another momentous event was the agreement reached to end years of civil war in Angola and to start a democratization process, a prime reflection of greater international cooperation between the United States and the Soviet Union.

In this, Soviet President Mikhail Gorbachev's open-mindedness in foreign affairs, shattering the Soviet rigidity of the past, has had a profound influence.

"It took the Soviet Union almost 30 years to recognize that much of what was happening in Africa could not be fitted into the grand ideological design," wrote Leonid Fituni, a director of the Institute for African Studies of the Soviet Academy of Sciences, in a recent article published by the Center for Strategic and International Studies in Washington.

Instead, Fituni wrote, the Soviets have designed a policy for Africa that abandons the confrontations of old in favor of cooperation in more pragmatic concerns.

The regime of Ethiopia's former ruler, Mengistu Haile Mariam, arguably suffered more than most Third World client states from this sea change in foreign attitudes. After receiving more than $10 billion in Soviet military aid during the 1980s, the Ethiopian ruler found himself starved for aid and under increasing pressure to liberalize the political and economic system -- pressures that only added to the eventual disintegration of his government.

The United States has moved into the political vacuum of this Soviet ideological retreat, as was underscored by Assistant Secretary of State Herman Cohen's efforts this week to mediate among Ethiopian parties that have all expressed favor for Marxism in the past.

But what is America's interest in Africa now that the Cold War is over?

U.S. officials argue that economic development and humanitarian concerns play a part, particularly at a time when an estimated 7 million Ethiopians are threatened by famine.

American policy makers are also concerned about containing anarchy and chaos -- such as that in Liberia and Somalia -- as the continent struggles for political change.

And while, as Joseph said, "Europe and the Soviets are willing to let America take the lead," geopolitical factors certainly still play a role.

Western analysts say U.S. officials remain concerned about the influence of Libyan leader Moammar Gadhafi in Africa and are particularly worried by his close ties to the victorious rebels in Eritrea.

But perhaps most important, shorn of more pressing geopolitical concerns, American interests may finally be linked as never before to a true development of political pluralism in Africa -- and, by extension, to human development.

Ake termed this an "American hegemony" in Africa, but it doesn't worry him for now, he said.

"This flexibility is giving room for a political realignment and renewal that Africa needs," he said. "It is improving the consciousness of ordinary people that things can change. . . . I don't think Africa's lived through a period in modern times when its collective consciousness has changed so much."

Ethiopia: Rebel soldiers stormed the capital on Tuesday, just a week after former Marxist president Mengistu Haile Mariam fled the country.

Angola: An agreement to be signed today between the government and U.S.-backed rebels could end 30 years of nearly constant warfare.

Somalia: War, social and political anarchy plague the country abandoned by president Siad Barre more than three months ago.

Zaire: Long a staunch ally of the U.S., Zaire faces profound political and economic crises that may threaten President Mobutu Sese Seko.

Congo, Cameroon, Togo: Authoritarian regimes in these nations have been forced to accept pluralistic reforms.

Benin: Economist Nicephore Soglo bercame president last month, after defeating dictator Mathieu Kerekou in the country's first free elections.

Mali: A coup in March toppled president Moussa Traore after 22 years in power and established a multi-party democracy.

Ivory Coast: President Felix Houphouet-Boigny, Africa's longest-serving leader, faces increasing pressure for democratization.

Liberia: Remains a divided country months after its government collapsed. Capital is controlled by a West African peace-keeping force; the rest of the nation by the National Patriotic Front.

Cape Verde Islands: The republic's first freely-elected president took office earlier this year.

Sao Tome and Principe: Held its first multi-party presidential vote in March.