The madman theory was a primary characteristic of the foreign policy conducted by U.S. President Richard Nixon. His administration, attempted to make the leaders of other countries think Nixon was mad, and that his behavior was irrational and volatile. Fearing an unpredictable American response, leaders of hostile Communist Bloc nations would avoid provoking the United States.

Nixon explained the strategy to his White House Chief of Staff, H. R. Haldeman:

I call it the Madman Theory, Bob. I want the North Vietnamese to believe I’ve reached the point where I might do anything to stop the war. We’ll just slip the word to them that, “for God’s sake, you know Nixon is obsessed about communism. We can’t restrain him when he’s angry—and he has his hand on the nuclear button” and Ho Chi Minh himself will be in Paris in two days begging for peace.

In October 1969, the Nixon administration indicated to the Soviet Union that “the madman was loose” when the United States military was ordered to full global war readiness alert (unbeknownst to the majority of the American population), and bombers armed with thermonuclear weapons flew patterns near the Soviet border for three consecutive days.

The administration employed the “madman strategy” to force the North Vietnamese government to negotiate a peace to end the Vietnam War. Along the same lines, American diplomats (Henry Kissinger in particular) portrayed the 1970 incursion into Cambodia as a symptom of Nixon’s supposed instability.

The madman strategy can be related to Niccolò Machiavelli, who, in his Discourses on Livy (book 3, chapter 2) discusses how it is at times “a very wise thing to simulate madness.”