To see the site is to know that the guardsmen were not under threat. The closest student killed, Jeffrey Miller, was 85 to 90 yards away, Allison Krause 100 yards, William Schroeder and Sandra Scheuer 130 yards.

Why, then, did it happen? The Guard was ill trained and ill led, mainly working-class young men resentful of the seemingly privileged students. Nothing can excuse the undisciplined shooting. But the deeper reasons lay in our national leadership: its obsessive pursuit of the Vietnam War, its paranoia, its mendacity.

"This is not an invasion of Cambodia," President Nixon had told the nation on April 30 as he disclosed that U.S. troops were invading Cambodia. A president who had campaigned on a promise to end the war was widening it. If he did not, he said, America would be "a pitiful, helpless giant."

American intelligence, we were told, had located a major North Vietnamese headquarters in Cambodia, and U.S. forces were going to seize it. What they found was a bunch of huts.

Americans who were not alive in 1970 must find it hard to understand why students at Kent State and other universities protested so emotionally over Vietnam. There were various reasons. But the underlying one was the government's persistence in a war whose futility was so overwhelmingly evident by then.

The Nixon administration had begun to reduce the American force in Vietnam that at its peak had exceeded 550,000. That was a creditable policy. But the administration confounded it by pretending that somehow South Vietnam could prevail without us.

The country was divided. President Nixon did not want to alienate those who believed in the war. But, fatally, he did not educate the country to understand the war's futility. To the contrary, he implied that victory was essential to our credibility -- to our not being seen as a pitiful, helpless giant.

In the years of the first Nixon administration, 1969 through 1972, the United States dropped four million tons of bombs on Indochina, and lost 20,492 American lives. Many times that number of Vietnamese were killed. To what end?

There was another, profound cost to the United States: the further polarization of our society, the shattering of common faith in government. Those wounds have not yet healed.

The attitudes that did such damage persist, too. They can be seen in the leading survivor among the policy makers of 1970, Henry Kissinger.

Writing in Newsweek on the legacy of Vietnam, Dr. Kissinger painted the critics of the war policy then as radical extremists who "challenged the very essence of American foreign involvement." Their legacy, he suggested, is in the Clinton administration.

"The conclusions that many in the Clinton administration -- and in the liberal community -- have drawn from the Vietnam War," he wrote, "present a profound challenge to traditional American foreign policy. They treat the cold war as a misunderstanding, if not an American creation."

In other words, liberals and the Clinton administration are soft on Communism. Try saying that to Madeleine Albright, Dr. Kissinger. Of course the overwhelming majority of liberal Americans supported the West's staunch and successful resistance to Soviet Communism, and look back at the policy with pride.

Dr. Kissinger always thought that criticism of U.S. foreign policy was somehow unpatriotic. The irony is that, out of office, he has become the most nagging of critics. Bosnia, Kosovo, East Timor: He has opposed one after another intervention to save human lives.

Criticism is valuable because it helps to correct public policies. That is a great advantage of open societies. But the system works only if those in charge are wise enough to recognize when a policy, however well intentioned, has gone wrong. The Vietnam War and its leaders are a monument to the failure of that necessary wisdom.

Copyright 2000 The New York Times Company

###