Twenty years ago this week, the world had a long, sweaty glimpse into what John F. Kennedy, tour guide for the occasion, called the "abyss of destruction." This was the 13-day "Cuban Missile Crisis," as it came to be called. Nikita Khrushchev had tried to slip intermediate-range nuclear missiles into Cuba. Kennedy pushed him to remove them. He did so.

As one who never doubted the necessity for Kennedy's firm response -- a combination of blockade and diplomatic pressure -- I find little value to the revisionist second thoughts lavishly provided us two decades later. It is unfashionable today to take presidential explanations at face value. Much presidential credibility, probably too much, was erased by the deceptions of Vietnam and Watergate. But there is no good reason to doubt that Kennedy stated his worries about the Soviet missiles in Cuba honestly and precisely on the early evening of Oct. 22, 1962.

First, Kennedy charged, the Soviet premier had attempted to change the balance of power suddenly, secretly, swiftly and stealthily. Thitherto, he said, the United States and the Soviet Union had tried to avoid surprising one another with nuclear deployments and redeployments. If surprise became the pattern, terrible instability would follow.

Second, Kennedy said, it would be dangerous to peace if stealthy aggression passed unchallenged. That was, he said, the "clear lesson" of the 1930s.

Today we know more than we knew then of the background. We know that the Soviet strategic nuclear force was then crude, unreliable and inaccurate, incapable of precision delivery at intercontinental ranges--by guided missile or bomber. The acceptance of IRBMs in Cuba, within close range of Eastern U.S. cities and bases, would indeed have altered the balance of power.

Those who doubted John Kennedy's judgment and motives then (or now) forget the long political buildup that preceded the missile crisis. It ran from Kennedy's own overheated reaction to Fidel Castro in 1960 through the Bay of Pigs fiasco to Sen. Kenneth Keating's insistence, weeks before, that the Russians were turning Cuba into a missile base.

For those reasons alone, a supine response was not in the cards. But people also forgot -- maybe Khrushchev did as well -- that Kennedy as a college boy had studied England's inadequate response to Hitler and published a senior thesis, "Why England Slept," about it. Kennedy spoke with modest historical authority when he said on Oct. 22 that "aggressive conduct, if allowed to go unchecked and unchallenged, ultimately leads to war." Here, well before Vietnam, was an enunciation of the famed "Munich Analogy."

In the long term, it was not to matter, militarily, whether the Russians placed IRBMs in Cuba. The time would come, soon enough, when the improved range and accuracy of Soviet ICBMs made the point moot. But power, as Kennedy understood, is not just firepower and arms. It is also will, resolution, character and adherence to well-founded historical values.

As a student of the '30s, Kennedy knew it was not Britain's lack of military power alone that made appeasement disastrous. It was the abandonment by Neville Chamberlain of Britain's historic policy of the grand coalition against European aggressors. He was determined that this costly error not recur. And it did not. It was a scary time. But on balance it was worth every drop of sweat it caused.