Fate of Communist Expeditionary Forces in a Nuclear WW3?

As some may know, the Soviet Union and Cuba sent troops to several armed conflicts in Africa during the Cold War. One being the Ogaden War, the other being the Angolan Civil War. The question posed here is while these thousands of troops are off fighting, a chain of events occurs that leads to a conventional third world war, soon followed by a full nuclear escalation between NATO and the WP. So what would these forces do? Carve a path back home? Stay in these countries and try to maintain order/finish their mission?
 
Depends on when the war is. If it happens in the 1960s, they probably either try to make it back, or more likely realize that their homeland is gone and hold out in the Third World. If the war is in the late 1970s or 80s they either die or get stuck in the post-apocalyptic ruins.
 
In the World war III TL 1983 Doomsday, Cuba was only lightly targetd by the US, and thus was still a functioning nation post WW3. As a result, Cuban forces in Africa were successfully brought back home.
 
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