More can be written, but you might like to start with these previous discussions:

• "Did Nixon really sabotage the 1968 Paris Peace Accords for his election? What evidence exists and why isn't this more important than Watergate?" by /u/bdhamp, looking at it from the U. S. side
• "How complicit was Richard Nixon in sabotaging the 1968 Vietnam Peace Talks? Why was it not exposed prior to the election? If true, did it amount to treason or similar capital offense?" by /u/Lich-Su, looking at it from the South Vietnamese side

This is not to discourage discussion. More questions, data and debate are welcome.