The resignation of Cuba's long-time leader, Fidel Castro, has focused attention on Cuba's sometimes controversial relations with Africa. These began with troops and aid to liberation movements and newly independent governments and continue today in the fields of health, education and sport. Southern Africa correspondent Scott Bobb takes a look at the relationship from our bureau in Johannesburg.

In 1975, Fidel Castro sought to justify the deployment of 30,000 Cuban troops to Angola, telling the United Nations General Assembly that imperialist nations were trying to gain control of its petroleum.

Castro said that unlike these forces, Cuba had no interest in Angola's mineral wealth but was supporting Angolan nationalism which he called an "international duty."

Over the next 15 years, several-hundred-thousand Cuban soldiers would fight in Angola and more than 2,000 would die there. They supported the Angolan government in its battle with Jonas Savimbi's UNITA which was backed by South Africa and the United States.

In one of the ironies of the Cold War, Cuban troops were sent to the Angolan enclave of Cabinda to guard employees of U.S. oil companies against attacks by rebels backed by U.S. allies.

A history professor at the University of Angola in Luanda, Immanuel Mwanza, says most Angolans have good memories of the Cuban presence.

He says in the context of the 1970s, when Angola was being invaded by apartheid South Africa, Cuban aid was fundamental to the nation.

Cuban troops began withdrawing after a 1988 agreement between Angola and South Africa that also led to the independence of Namibia two years later.

Cuban troops were involved in other conflicts on the continent. And at one point Havana had some 60,000 troops stationed in 17 African nations.

Today many Cuban professionals still work in hospitals in Africa's rural areas and in medical schools in the cities. Havana also has educational and sports exchanges with dozens of African nations.

Mwanza of Angola University says this type of aid has been the most useful.

He says we should have learned better from Cuba, how to manage the economy, how a country with few resources can resist. And we should have learned from Cuba's school and health systems.

Analysts note that Cuba's military and social programs in Africa drained resources from the Cuban economy and, in the late 1980s, consumed some 10 percent of the government's annual budget.

The Cuban presence also placed additional strains on its already poor relations with western nations and their allies.

However, African leaders have not forgotten Cuba's support. And most continue to maintain warm relations with Havana to this day.