How do nuclear capabilities primarily deter aggression?

Nuclear capabilities primarily deter aggression through the threat of massive retaliation. This concept is grounded in the understanding that the possession of nuclear weapons serves as a powerful deterrent against potential aggressors. The rationale is straightforward: if an adversary knows that an aggressive action could result in a devastating nuclear response, they are less likely to engage in such behavior.

The principle of mutually assured destruction (MAD) underpins this deterrence strategy. In a nuclear confrontation, the certainty of catastrophic consequences for both the attacker and the defender creates a strong incentive to avoid conflict altogether. This psychological deterrent effect is what makes nuclear capabilities a significant factor in international relations, as the fear of total annihilation can prevent conflicts from escalating to that level.

While alliances, humanitarian aid, and intelligence are important aspects of modern geopolitics and military strategy, they do not serve the same immediate and visceral deterrent effect that the existence of nuclear weapons confers. Therefore, the threat of massive retaliation is recognized as the core mechanism through which nuclear capabilities deter aggression.