"His administration, the executive branch of the federal government of the United States from 1969 to 1974, 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."

http://en.wikipedia.org/wiki/Madman_theory

I like better sources that poorly sourced Wikipedia articles for controversial statements like this. I'm not sure I have enough evidence to believe the statement in your kind comment. (I'm a Wikipedian, which is why I'm deeply dubious about politically tendentious statements cited to Wikipedia.)

I have read other accounts of that "strategy" being used by Nixon - would take me a while to find the exact references so I used that Wikipedia article.