Amazon.com description: Product Description: Why did the Soviet Union use less force to preserve the Soviet empire from 1989 to 1991 than it had used in distant and impoverished Angola in 1975? This book examines how actors' preferences and causal conceptions change as they learn from their experiences. Andrew Bennett draws on interviews and declassified Politburo documents as well as numerous public statements to establish the views of Soviet and Russian officials. He argues that Soviet leaders drew lessons from their apparent successes in Vietnam and elsewhere in the 1970s that made them more interventionist.