Presidential adviser Henry A. Kissinger '50, confirmed Saturday that the United States and North Vietnam have not yet reached an agreement that President Nixon considers "just and fair."

Kissinger cautioned newsmen that he did not yet consider the recent series of secret negotiations completed, because two obstacles remained.

First, he said that North Vietnam and the United States are "at drastic variance" in their perceptions of the international machinery to supervise the ceasefire in Vietnam. Second, he indicated that Washington could not go along with a settlement that "brings peace to North Vietnam" but allows Hanoi "the right of constant intervention in the South."

During the talks which began on December 4, North Vietnam revoked its agreement of two weeks earlier on the guarantee of South Vietnam's sovereignty, Kissinger said. In the recent talks, the North Vietnamese hid their disagreements on many issues "in the guise of linguistic changes," the presidential adviser said.

"It cannot do that every day... when an issue is settled in an agreement, it is raised again as an understanding. And if it is settled as an understanding, it is raised again as a prototocol," Kissinger said.

While he said he sympathized with the concerns of the Saigon government, Kissinger pointed out that the U.S. would proceed with the implementation of a "just settlement" once it is reached. He added that it would be unfair to consider Saigon as the obstacle to an agreement, " because we do not as yet have an agreement to present to them."