Nuclear blackmail is a form of nuclear strategy in which an aggressor uses the threat of use of nuclear weapons to force an adversary to perform some action or make some concessions. It is a type of extortion, related to brinkmanship.
Nuclear blackmail is considered most effective when the person making the threat is unhinged and ostensibly willing to commit suicide. (See game theory). The prevention of these threats by irrational actors is the stated purpose behind the National Missile Defense program undertaken by President George W. Bush of the United States.
It is generally regarded as ineffective against a rational opponent who has or is an ally of someone who has assured destruction capability. If both states have nuclear weapons, the form of nuclear blackmail becomes a threat of escalation. In this situation if the opponent refuses to respond, then one's choices are either surrender or suicide. During the Cold War, the explicit threat of nuclear warfare to force an opponent to perform an action was rare in that most nations were allies of either the Soviet Union or the United States.
In 1953, Eisenhower threatened the use of Nuclear Weapons to end the Korean War if the Chinese refused to negotiate. Consequently the Chinese and North Korea signed the Armistice. 
The United States issued several nuclear threats against the People's Republic of China in the 1950s to force the evacuation of outlying islands and the cessation of attacks against Quemoy and Matsu, part of Republic of China.
Recently declassified documents from the National Archives (UK) indicate that the United Kingdom considered threatening China with nuclear retaliation in 1961 in the case of a military reclamation of Hong Kong by China.
 In fiction
Nuclear blackmail, typically by a supervillain rather than a state, has been frequently employed as a plot device in spy fiction and action films. Since such a scheme appeared in the film Thunderball, the trope has been particularly associated with the James Bond series and in 24 (TV series). The notion of a supervillain threatening world leaders with a nuclear device has since become a cliché, and has been parodied in Charles K. Feldman's Casino Royale, Austin Powers: International Man of Mystery, The Simpsons episode "You Only Move Twice", and other espionage spoofs.
 See also
- Deterrence theory
- Essentials of Post–Cold War Deterrence
- Mutual assured destruction
- Nuclear stonewalling
- Nuclear terrorism
- Samson Option
- Edward Friedman, “Nuclear Blackmail and the end of the Korean War,” Modern China 1 1 (Jan. 1975), 75-91.
- "UK pondered China nuclear attack". BBC News. 2006-06-30.
- "Thatcher 'threatened to nuke Argentina'". The Guardian. 2005-11-22.