"A whole civilization will die tonight, never to be brought back again."

These are not the words of Hitler, or Stalin, or Mao, or Pol Pot, or Assad, or Putin. These are the words of the president of the United States, today.

Do not be distracted by circumstances. Of course there are emotions, personalities, politics, a war. None of this excuses that sentence. The reason we have a notion of genocide, and a convention on genocide, is to define certain actions as always and definitively wrong.

Are these "only words"? No, they cannot be "only words." As any historian of mass atrocity knows, there is no such thing as "only words." The notion of killing a whole civilization, once spoken, remains. It enables others to say similar things, as when another elected representative compared the entire country of Iran to a cancer that had to be removed.

Whatever happens tonight, the president, by saying such things, has already changed the world for the worse, and made acts of mass violence more likely. If we are Americans, he has also changed our country. He has changed us, because he represents us; we voted for him, or we didn't vote and allowed him to come to power, or we didn't do enough to stop him. These words are America's words, until and unless Americans reject them.

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