In July 1965, an American diplomat in Paris, Ed Gullion, opened up secret talks with Mai Van Bo, who headed the National Liberation Front's office in Paris. To provide secrecy, Gullion was code-named R. Bundy advised Johnson to let the talks proceed, writing: "Let R do the talking this time and see if there is any give in his position". However, the XYZ talks as the negotiations were called floundered over the demand that the United States unconditionally cease bombing North Vietnam as a precondition for peace talks.