Was Nixon's "Madman Theory" effective?

Question

Definition of "Madman Theory":

The madman theory is a political theory commonly associated with U.S. President Richard Nixon's foreign policy. He and his administration tried to make the leaders of hostile Communist Bloc nations think Nixon was irrational and volatile. According to the theory, those leaders would then avoid provoking the United States, fearing an unpredictable American response.

[ Wikipedia ]

A more detailed description with links to source material.

President Richard Nixon and his national security adviser Henry Kissinger believed they could compel "the other side" to back down during crises in the Middle East and Vietnam by "push[ing] so many chips into the pot" that Nixon would seem 'crazy' enough to "go much further," according to newly declassified documents published today by the National Security Archive.

The documents include a 1972 Kissinger memorandum of conversation published today for the first time in which Kissinger explains to Defense Department official Gardner Tucker that Nixon's strategy was to make "the other side ... think we might be 'crazy' and might really go much further" — Nixon's Madman Theory notion of intimidating adversaries such as North Vietnam and the Soviet Union to bend them to Washington's will in diplomatic negotiations.

[ National Security Archive ]

The goal was to get our adversaries to bend to "Washington's will in diplomatic negotiations". I have found no authoritative evidence that the Madman Theory was or was not effective at achieving Nixon's goals.

The Wiki article quotes Scott Sagan as saying the theory was "ineffective and dangerous". The article quoted does make this argument but the same paper says "We have little evidence indicating what the Soviet leaders knew about the U.S. nuclear alert and how they interpreted it." The paper argues from silence and does not address Nixon's goals for ordering the nuclear alert.

Evidence of effectiveness would indicate:

• The Vietnam War ended sooner or on more favorable terms.
• The Soviet Union reduced its support of North Vietnam or induced Hanoi to make diplomatic concessions.

Is there any evidence that the Madman Theory was effective?

Answer 1

Well, by Nixon's own standard, his implementation of it certainly wasn't very effective. As quoted by his chief of staff:

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.

This was in 1969 or earlier (as Ho died that year). There were ongoing negotiations (yes, in Paris) since before Nixon took office, but the general North Vietnamese tactic was always to keep talking and keep fighting. After Nixon took office, The talks were completely deadlocked for the next 3 years. When the deadlock was broken in 1972, the agreement reached was for a cease-fire, followed by a US (but not North Vietnamese) withdrawl. Given how much longer that agreement took, and how the North seems to have very much gotten the better side of the deal, I think its quite fair to say that no "begging for peace", or in fact anything close to it, happened as a result of Nixon's policy behavior.