Why could nuclear weapons not deter every type of conflict during the Cold War?

During the Cold War, nuclear weapons could not deter every type of conflict because the doctrine of mutual assured destruction (MAD) was primarily designed to prevent a direct, all-out nuclear exchange between superpowers. This created several limitations:12

• Credibility and Proportionality: Policymakers recognized that threatening a massive nuclear strike was often not a credible response to smaller provocations or conventional aggression, as the cost of such an action would be disproportionately catastrophic for both sides.34
• Asymmetrical Warfare: The nuclear stalemate did not prevent "brushfire wars" or insurgencies, such as the Vietnam War, where communist forces utilized guerrilla tactics that were ill-suited for a nuclear response.15
• Limited War Strategies: As the fear of total annihilation grew, both sides explored limited nuclear options (LNO) and conventional military strategies. Critics argued that these shifts made "little wars" more permissible, as they reduced the taboo against using nuclear weapons in smaller, localized conflicts.34
• Strategic Interests: Deterrence failed to address conflicts where vital national interests were not directly engaged or where adversaries sought to gain regional advantages without triggering a global holocaust.345