Seventy-two years ago this week the United States committed war crimes against the Japanese people on a scale that was previously unimaginable in human history.

It is almost impossible to utter this truism in public without being subjected to a chorus of tediously well-rehearsed, half-understood objections learned from high-school classrooms, pop history, and talk radio. The most common form these replies take is that, so far from being acts of state-sponsored mass murder, the atomic bombings of Hiroshima and Nagasaki were humanitarian missions meant primarily to save lives: Had it not been for the instantaneous slaughter of some 220,000 people (a conservative estimate), mainly civilians, the war would have been unnecessarily prolonged. It was far better, assuming those projected casualty figures, which since at least 1947 have routinely been estimated upward after the fact, to kill a few hundred thousand civilians rather than risk an equal or greater number of dead American and Japanese soldiers.

If this would-be lofty motive were behind the bombings, it would certainly have come as a surprise to President Harry Truman and the American people at the time. Nothing could be more grimly clarifying than the words with which Truman broke the news of Hiroshima to the American people, an address worthy of a Star Wars villain in which he made it clear that he considered the attack, and its forthcoming sequel, a mission of revenge and spoke rapturously of the "marvel" he had unleashed upon the Japanese and the "achievement of scientific brains" that had made it possible:

Sixteen hours ago an American airplane dropped one bomb on Hiroshima, an important Japanese Army base. That bomb had more power than 20,000 tons of T.N.T. It had more than two thousand times the blast power of the British "Grand Slam" which is the largest bomb ever yet used in the history of warfare.

The Japanese began the war from the air at Pearl Harbor. They have been repaid many fold. And the end is not yet. With this bomb we have now added a new and revolutionary increase in destruction to supplement the growing power of our armed forces. In their present form these bombs are now in production and even more powerful forms are in development.

It is an atomic bomb. It is a harnessing of the basic power of the universe. The force from which the sun draws its power has been loosed against those who brought war to the Far East. [Truman]

But the truth is that it doesn't matter what the motivation was. The indiscriminate targeting of civilians in warfare is always evil. It was evil when the Germans engaged in it during the Blitz; it was evil when the Royal Air Force, amid almost no protests save from a lone Anglican bishop, firebombed Dresden. It was unspeakably, blasphemously, indescribably evil during the Rape of Nanking (if you can read Iris Chang's book without coming close to despair, your stomach is stronger than mine). It is one thing to take military action in full knowledge of the fact that the innocent may be harmed in pursuit of a just end (for example, targeting a military base where there may be civilian employees); this is in keeping with a principle that philosophers and theologians call "double effect" — it is something else entirely to make the harming of innocents the end in itself.

Another related objection is a tired ad hominem that seeks to prevent anyone who was not alive and in uniform at the time of the bombings from passing judgment. The historian Paul Fussell said something like this in "Thank God for the Atom Bomb," a famous essay published in the New Republic in 1981. After tut-tutting John Kenneth Galbraith and others who have suggested that the bombings were neither morally justifiable nor militarily expedient, Fussell points out that "what's at stake in an infantry assault is so entirely unthinkable to those without the experience of one, or several, or many, even if they possess very wide-ranging imaginations and warm sympathies… [E]xperience is crucial."

Like all arguments of this kind, Fussell's is dead on arrival. If it is the case that people who have never fought in a World War II-era infantry assault should refrain from opining on the morality of atomic weaponry, then no one in holy orders, no women, no persons with physical disabilities are permitted to have opinions about these important moral questions. Besides, one might ask, who is Paul Fussell or anyone else who has never watched the skin be ripped from human faces, their features turned to Stygian leather, their voices reduced to low grunts, carrying with charred stumps the blackened remains of an infant, to pronounce on the morality of Hiroshima? The experience thing cuts both ways.

Conservatives and hard-nosed centrists tend to scoff at the idea of a world without nuclear weapons. I cannot think why. This is not some hippie fantasy. It was the great dream of Ronald Reagan, that wimpy arch-liberal cry-baby, the animating force behind the Strategic Defense Initiative and the Reykjavík Summit of 1986 that led to the signing of the Intermediate-Range Nuclear Forces Treaty. It has been the unchanged teaching of the Catholic Church throughout the post-war era. It is perhaps the only cause to have united Msgr. Ronald Knox, Barbra Streisand, and Colin Powell, among other luminaries.

With North Korea making what looks like rapid progress in the pursuit of its own nuclear arsenal, Prime Minister Shinzo Abe's recent call for us "to truly realize a world without nuclear weapons" has rarely been more timely or more desperate.