Pope Francis (Filippo Monteforte/Agence FrancePresse/Getty Images)

IN OFFHAND comments on June 21, Pope Francis raised a difficult question about the Holocaust: Why didn’t the Allies bomb the rail lines to Auschwitz? The context of the remark was his concern about refugees flooding across borders in North Africa and the Middle East, victims of war, repression and deprivation. The pope admonished the rest of the world for being insensitive to their plight and recalled examples from history: the Armenian genocide, Stalin’s gulag and the Nazi concentration camps. “The great powers had photographs of the railways that brought trains to the concentration camps, to Auschwitz, to kill Jews, Christians, Gypsies, homosexuals,” the pope said. “But tell me why didn’t they bomb them?”

Certainly, there is evidence that the United States and United Kingdom knew of the Nazi camps, based on reports from Poles and other sources. Our point here is not to render a judgment on this complex history and failure to act but to draw from it an important and urgent lesson for today: Knowing about such tyrannical behavior brings a responsibility to do something about it.

Often it is declared that “never again” is the prime lesson of the Holocaust and other genocidal events of the modern era. The pope’s comment reminds us not only to look back but also to confront today’s abuses. Methods now exist to detect and track horrors that were not available at the time of Auschwitz, including satellite photography that can reveal facts on the ground even in the most forbidden zones.

More than a year ago, a United Nations commission of inquiry showed with persuasive detail and clarity that North Korea maintains prison camps every bit as reprehensible and worrisome as those of Hitler and Stalin. The report found that four large camps in North Korea hold some 80,000 to 120,000 political prisoners. The commission declared in its report that “crimes against humanity” were committed and based on policies set at the top of the regime. The commission, which was never allowed to enter North Korea but interviewed a wide range of witnesses, reported evidence of “extermination, murder, enslavement, torture, imprisonment, rape, forced abortions and other sexual violence, persecution on political, religious, racial and gender grounds, the forcible transfer of populations, the enforced disappearance of persons and the inhumane act of knowingly causing prolonged starvation.”

Since this report was issued, the world has responded with lassitude. The U.N. General Assembly passed a resolution urging referral of North Korea to the International Criminal Court, but the resolution stalled in the Security Council, which has not voted, largely because of the expectation that China, North Korea’s longtime benefactor and neighbor, would veto it. A U.N. human rights office is finally opening in Seoul to track abuses in the north, which may eventually help bring Pyongyang’s leaders to account. But this is a baby step in the face of a monstrous killing machine. It is hardly enough. At stake is the same moral issue raised by the pope’s question about Auschwitz. Doing nothing should not be an option.