DEAR STUDENT LEADERS:

I have received and read carefully your thoughtful letter to the President about our policy in Vietnam.

Your interest and your concern are shared by most thinking Americans. No one desires more strongly to bring an early and honorable conclusion to the conflict in Vietnam than those who are working day and night, both here and in Vietnam, to achieve that end.

The questions you have raised are among those that have been asked and discussed repeatedly in the councils of your Government. If some of these matters continue, as you say, to agitate the academic community, it is certainly not because answers have not been provided. It is more, I think, because the answers to great and complex questions can never fully satisfy all the people in a free and questioning society.

Nevertheless, I am glad to have the chance to address myself to the four specific questions about which you and others felt doubt or concern.

First, you asked if America's vital interests are sufficiently threatened in Vietnam to necessitate the growing commitment there.

There is no shadow of doubt in my mind that our vital interests are deeply involved in Vietnam and in Southeast Asia.

We are involved because the nation's word has been given that we would be involved. On February 1, 1955, by a vote of 82 to 1 the United States Senate passed the Southeast Asia Collective Defense Treaty. That Treaty stated that aggression by means of armed attack in the treaty area would endanger our own peace and safety, and, in that event, "we would act to meet the common danger." There is no question that an expanding armed attack by North Vietnam on South Vietnam has been under way in recent years; and six nations, with vital interests in the peace and security of the region, have joined South Vietnam in defense against that armed attack.

Behind the words and the commitment of the Treaty lies the lesson learned in the tragic half century since the First World War. After that war our country withdrew from effective world responsibility. When aggressors challenged the peace in Manchuria, Ethiopia, and then Central Europe during the 1930's, the world community did not act to prevent their success. The result was a Second World War -- which could have been prevented.

That is why the Charter of the United Nations begins with these words: "We the peoples of the United Nations, determined to have succeeding generations from the scourge of war, which twice in our lifetime has brought sorrow to mankind..." And the Charter goes on to state these objectives: "to establish conditions under which justice, and respect for the obligations arising from treaties and other sources of international law can be maintained ... and to unite our strength to maintain international peace and security..."

This was also the experience President Truman had in mind when--at a period when the United Nations was incapable of protecting Greece and Turkey from aggression -- he said: "We shall not realize our objectives unless we are willing to help free peoples to maintain their free institutions and their national integrity against aggressive movements that seek to impose upon them totalitarian regimes."

These are the memories which have inspired the four postwar American Presidents as they dealt with aggressive pressures and thrusts rfom Berlin to Korea, from the Caribbean to Vietnam.

In short, we are involved in Vietnam because we know from painful experience that the minimum condition for order on our planet is that aggression must not be permitted to succeed. For when it does succeed, the consequence is not peace, it is the further expansion of aggression.

And those who have borne responsibility in our country since 1945 have not for one moment forgotten that a third world war would be a nuclear war.

But the hard and important fact is that in the postwar world external aggression has not been permitted to develop its momentum into general war.

Look back and imagine the kind of world we now would have if we had adopted a different course. What kind of Europe would now exist if there had been no commitment to Greece and Turkey? No Marshall Plan? No NATO? No defense of Berlin? Would Europe and the world be better off or worse? Would the possibilities of detente be on the present horizon?

Then turn the globe and look at Asia. If we had made no commitments and offered no assistance, what kind of Asia would there now be? Would there be a confident and vital South Korea? A prosperous and peaceful Japan? Would there be the new spirit of regional cooperation and forward movement now developing throughout Asia?

If you were to talk to the leaders of Asia as I have, you would know that the new vigor in Asia, the new hope and determination, are based in part on the conviction that the United States will continue to support the South Vietnamese in their struggle to build a life of their own within the framework of the Geneva Accords of 1954 and 1962 -- that we shall see it through to an honorable peace.

Second, you wonder whether our vital interests are best protected by our growing commitment.

We must always weigh what we are doing against the requirements of the situation and what the other side is doing. You are aware, I am sure, that the flow of men and material from North Vietnam into the South radically increased towards the end of 1964 and continued at a high level in the next two years. It was to meet that escalation, designed to achieve military victory by the North against the South, that we sent our men in large numbers and began an air campaign against military targets in North Vietnam.

At the other end of the scale, one must contrast what we are doing with what we could be doing. You know the power that is available to us--in men, resources and weaponry.

We have done both more than some people would wish, and less than other advocate. We have been guided both by the demands imposed upon us by increased aggression and by the need for restrtaint in the application of force. We have been doing what the President judges to be necessary to protect the nation's vital interests, after hearing the views of the government's military and civilian experts. We shall continue to do what is necessary to meet the threat the Vietnamese and their allies face.

Third, you raise the question whether a war that may devastate much of the countryside can lead to the stable and prosperous Vietnam we hope for.

First, it is an error to suggest that the fighting in Vietnam has devastated "much of the countryside." There has been too much destruction and disruption -- as there is any war. And we deeply regret the loss of life that is involved -- the South and in the North among both soldiers and civilians.

But devastation has been far less than on the conventional battlefields of World War II and Korea. If peace could come to South Vietnam today, I think most people would be amazed at its rapid recovery. For the Vietnamese are intelligent, energetic, and ambitious people. And they are determined to see their country prosper. I am confident that they can achieve that end -- if they but have the chance to do so, in peace and in their own way.

That day cannot come too soon.

You also suggest that there are "apparent contradictions" in the American position on efforts to achieve a negotiated settlement.

We have said that there will be no difficulty in having the views of the Viet Cong presented at any serious negotiation. The details of how this might be done can be discussed with the other side; there is little point in negotiating such details with those who cannot stop the fighting.

We have made it clear that we cannot accept the Liberation Front as the "sole" or "only legitimate voice" of