Why did foreign countries get involved in the Angolan Civil War from 1975?

The key question is: "Research why Foreign Countries become involved in the Angolan Civil War from 1975."

The line of argument will assert that foreign intervention in the Angolan Civil War was primarily driven by a confluence of Cold War geopolitical rivalries, the strategic importance of Angola's natural resources, and regional security concerns. Different external actors supported various Angolan factions based on ideological alignment, economic interests, and their own national security agendas, transforming the internal conflict into a major proxy war.