HIROSHIMA, Japan — President Barack Obama paid tribute Friday to the “silent cry” of the 140,000 victims of the atomic bomb dropped 71 years ago on Hiroshima, and called on the world to abandon “the logic of fear” that encourages the stockpiling of nuclear weapons.

Obama’s trip to Hiroshima made him the first U.S. president to visit the site of the world’s first atomic bomb attack, and he sought to walk a delicate line between honoring the dead, pushing his as-yet unrealized anti-nuclear vision and avoiding any sense of apology for an act many Americans see as a justified end to a brutal war that Japan started with a sneak attack at Pearl Harbor.

“Death fell from the sky and the world was changed,” Obama said, after laying a wreath, closing his eyes and briefly bowing his head before an arched stone monument in Hiroshima’s Peace Memorial Park that honors those killed on Aug. 6, 1945. “The flash of light and a wall of fire destroyed a city and demonstrated that mankind possessed the means to destroy itself.”