Today is the 65th anniversary of the U.S. bombing of Nagasaki—one of the largest single-day atrocities ever committed by a war power.

The bomb instantly killed about 70,000 people, mostly civilians, and thousands more died painful deaths later from radiation.

The Nagasaki bombing, even more than Hiroshima, was inexcusable.

Both were unnecessary, because the Japanese were already trying to negotiate a surrender, and the United States could have used a “demonstration bomb” over an uninhabited island to prove the destructiveness it was prepared to deliver.

But Truman and the Pentagon were dead set on dropping the bomb.

In Howard Zinn’s final book, The Bomb, he writes: “The persistent notion that the Japanese were less than human probably played some role in the willingness to wipe out two cities populated by people of color.”

Zinn also demolishes the “military necessity” argument. He notes that “the Japanese Supreme War Council authorized Foreign Minister Togo to approach the Soviet Union ‘with a view to terminating the war if possible by September.’ ”

And he quotes a July 13, 1945, wire from Foreign Minister Togo: “Unconditional surrender is the only obstacle to peace. . . . It is His Majesty’s desire to see the swift termination of the war.”

Zinn cites the scholarship of Gar Alperovitz and argues that the chief reason for the bombing was to intimidate the Soviet Union.

“The United States was more anxious to show the world—especially the Soviet Union—its atomic weaponry than to end the war as soon as possible,” Zinn writes. He quotes Harry Truman’s comment after learning that Stalin was intending to invade Japan: “Fini Japs when that comes about.”

Zinn comments about Truman: “It seems he did not want the Japs to be ‘fini’ through Russian intervention but through American bombs.”

Zinn also quotes General Dwight D. Eisenhower’s dissent at the time. “I voiced to [General Stimson] my grave misgivings, first on the basis of my belief that Japan was already defeated and that dropping the bomb was completely unnecessary, and secondly because I thought that our country should avoid shocking world opinion by the use of a weapon whose employment was, I thought, no longer mandatory as a measure to save American lives.”

Even if you accept the “military necessity” argument for the Hiroshima bomb, which Zinn rejects, how can you possibly justify Nagasaki?

The United States, just three days before, had annihilated 140,000 men, women, and children in Hiroshima. That makes Nagasaki the most lethal redundancy in military history.

“The preparations had been made and just went ahead without further thought,” Zinn writes. “One reason for the absence of discussion may well have been that while the Hiroshima bomb fissioned only uranium atoms, the Nagasaki bomb used plutonium, and there was a question whether the plutonium would work as well.”

Kurt Vonnegut called the gratuitous bombing of Nagasaki “the most racist, nastiest act by this country, after human slavery,” in an interview by David Barsamian in The Progressive.

President Obama had the decency to send U.S. Ambassador John Roos to Hiroshima’s memorial service on Friday. He should have had the decency to send Roos to Nagasaki, too.

At the end of Zinn’s book, The Bomb, he urges us to “refuse to accept the idea, which is the universal justification for war, that the means of massive violence are acceptable for ‘good ends.’ ”

They are not.

That’s the universal meaning of Nagasaki.