To earn that sentence

Perversely, America's public awareness of the Holocaust often seemed to set the bar for concern so high that we were able to tell outselves that contemporary genocides were not measuring up. As the writer David Rieff noted, "never again" might best be defined as "Never again would Germans kill Jews in Europe in the 1940s."

...

To earn a death sentence, it was enough in the twentieth century to be an Armenian, a Jew, or a Tutsi. On September 11, it was enough to be an American. In 1994 Rwanda, a country of just 8 million, experienced the numerical equivalent of more than two World Trade Center attacks every single day for 100 days. On an American scale, this would mean 23 million people murdered in three months. [On an Indian scale, close to 100 million]. When, on September 12, 2001, the United States turned for help to its friends around the world, Americans were gratified by the overwhelming response. When the Tutsi cried out, by contrast, every country in the world turned away.

...

Citizens victimized by genocide or abandoned by the international community do not make good neighbours, as their thirst for vengeance, their irredentism, and their acceptance of violence as a means of generating change can turn them into future threats.

From Samantha Power's A Problem From Hell: America and the Age of Genocide. (My previous post about this book).