Mutually Assured Destruction (MAD) is a strategic condition, and the doctrine built around it, in which any nuclear first strike by one superpower would trigger a retaliatory strike of comparable or greater destructiveness, leaving both sides devastated. The logic is deterrence by punishment: because attack guarantees suicide, no rational actor will initiate one.
MAD emerged in the early 1960s as the Soviet Union closed the strategic gap with the United States and both sides fielded survivable second-strike forces — particularly submarine-launched ballistic missiles (SLBMs) and hardened ICBM silos. US Secretary of Defense Robert McNamara articulated "assured destruction" as a planning standard, requiring the ability to destroy a large share of Soviet population and industry even after absorbing a surprise attack. Critics, including physicist Donald Brennan who coined the acronym MAD in 1962, argued the posture was morally and strategically perverse.
Several conditions are usually identified as necessary for MAD to hold:
- Survivable second-strike forces (often via the nuclear triad of bombers, ICBMs, and SLBMs).
- Reliable command and control to guarantee retaliation.
- Mutual vulnerability of populations and economies, which is why missile defenses are seen as destabilizing.
- Rational adversaries who value national survival.
The doctrine shaped key Cold War arms control agreements. The 1972 Anti-Ballistic Missile (ABM) Treaty between the US and USSR explicitly limited strategic missile defenses to preserve mutual vulnerability. SALT I and later START agreements capped delivery vehicles and warheads to stabilize the balance. The US withdrew from the ABM Treaty in 2002, and debates over national missile defense, hypersonic weapons, and low-yield "usable" warheads have since reopened questions about whether MAD still adequately describes the US–Russia and emerging US–China nuclear relationships.
MAD is distinct from minimum deterrence (a smaller arsenal sufficient to inflict unacceptable damage) and nuclear war-fighting doctrines, which envision controlled, limited nuclear exchanges.