What did President Nixon demand of the North Vietnamese when he came into office?Because of this - why was the U.S. unable to reach a peace agreement with Vietnam in 1969?
Essentially, Nixon argued that the South Vietnamese needed to assume a greater role in the fighting. His policy of Vietnamization helped to encapsulate the Vietnam discussion as one where South Vietnamese forces could take on more responsibilities in the fighting, gradually removing the United States' onus of responsibility in the fighting. At the same time, using the presence of personality, Nixon was able to employ diplomacy as a means by which another goal could be accomplished. The idea of Nixon's "unpredictable" nature was used to emphasize to North Vietnamese that Nixon was a man who should not be questioned. The bombing of Cambodia and the expansion of internal bombing programs within Vietnam lent credence to this.
During the 1968 campaign, Richard Nixon said that he had a secret plan that would bring "peace with honor" in Vietnam. Part of that plan was to make demands of the North. Once he was in office, he had US negotiators in Paris tell the North Vietnamese what his demand was. His main demand was that the North should pull all of its military out of South Vietnam. Then the war could just be a civil war within the South.
The North had no desire to do this and so peace was not possible -- there was no middle ground that both the US and North Vietnam were willing to accept.