The wars of the modern age teach us this truth,” President Barack Obama remarked today during his trip to the Hiroshima Peace Memorial Park, the first by a sitting U.S. President. “Hiroshima teaches this truth. Technological progress without an equivalent progress in human institutions can doom us. The scientific revolution that led to the splitting of an atom requires a moral revolution as well.”

“Science allows us to communicate across the seas and fly above the clouds, to cure disease and understand the cosmos, but those same discoveries can be turned into ever more efficient killing machines,” he continued.

That is why we come to this place. We stand here in the middle of this city and force ourselves to imagine the moment the bomb fell. We force ourselves to feel the dread of children confused by what they see. We listen to a silent cry. We remember all the innocents killed across the arc of that terrible war and the wars that came before and the wars that would follow.

President Barack Obama embraces atomic bomb survivor Shigeaki Mori during his visit to the Hiroshima Peace Memorial Park on May 27, 2016 in Hiroshima, Japan. It is the first time U.S. President makes an official visit to Hiroshima, the site where the atomic bomb was dropped in the end of World War II on August 6, 1945.

Obama gave his speech after laying a wreath at the cenotaph, the central memorial that honors the victims of the bombing. Japan’s President Shinzo Abe said the visit represents a new era in reconciliation between the two nations.

“We come to mourn the dead, including over 100,000 Japanese men, women and children, thousands of Koreans, a dozen Americans held prisoner,” Obama said in a rare reference to the Koreans, then subjects of the Japanese Emperor, who were killed in the blast. American POWs also died in the atomic bombing.

“In the image of a mushroom cloud that rose into these skies, we are most starkly reminded of humanity’s core contradiction,” Obama said. “How the very spark that marks us as a species, our thoughts, our imagination, our language, our toolmaking, our ability to set ourselves apart from nature and bend it to our will — those very things also give us the capacity for unmatched destruction.”

“We may not be able to eliminate man’s capacity to do evil, so nations and the alliances that we form must possess the means to defend ourselves. But among those nations like my own that hold nuclear stockpiles, we must have the courage to escape the logic of fear and pursue a world without them,” Obama said.

Obama’s full remarks are available here.

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Photos via Atsushi Tomura/Getty