Nearly 71 years after the United States dropped the world’s first atomic bomb, President Barack Obama made an unprecedented journey here to offer a solemn tribute to the tens of thousands of victims and to amplify his quest for a world without nuclear weapons.

The first sitting U.S. president to visit Hiroshima silently placed a white-and-yellow wreath in front of a concrete, arch-shaped monument at the expansive Peace Memorial Park representing a shelter for the victims’ souls bearing an inscription in Japanese: “Let all the souls here rest in peace; For we shall not repeat the evil.” Then he closed his eyes and bowed his head for a moment.

“Seventy-one years ago on a bright cloudless morning, death fell from the sky and the world was changed,” Obama said in remarks a few minutes later. “A flash of light and a wall of fire destroyed a city, and demonstrated that mankind possessed the means to destroy itself.”

The atomic bomb killed an estimated 140,000 people in the western city of Hiroshima. Three days later, a second atomic bomb killed up to 80,000 people in Nagasaki, 260 miles away.

Obama had spoken about his desire to visit Hiroshima since his first days in the White House. But he waited until his final months in office to make a trip that would allow him to renew his push for a world free of nuclear weapons and to add final chapters to his record. After his visit, he immediately flew home, ending a weeklong trip to Asia.

The visit to Hiroshima was brief – lasting less than an hour – and carefully choreographed, but still full of symbolism and powerful messages.

Obama, walking alongside Japanese Prime Minister Shinzo Abe, spoke to a pair of bombing survivors, Sunao Tsuboi, who heads an organization for victims, and Shigeaki Mori, who created a memorial for American World War II prisoners of war killed in Hiroshima. At one point, Obama leaned in and gave Mori a gentle hug. The park was quiet except for helicopters buzzing overhead and the shutters of hundreds of cameras.

The two leaders walked through the park and stood briefly before the most famous symbol of the events of Aug. 6, 1945, the domed ruins of the former Hiroshima Prefectural Industrial Promotion Hall, the building closest to the center of the blast site. They walked past a 52-year flame that will remain lit until all nuclear bombs are destroyed.

Obama signed a guest book: “We have known the agony of war. Let us now find the courage, together, to spread peace, and pursue a world without nuclear weapons.”

Abe called Obama’s decision to come to Hiroshima courageous and said it showed the ties between two nations that have transformed from enemies into friends.

In Hiroshima, many people said they were grateful that Obama came, most saying they weren’t bothered that it took this long or that he didn’t apologize for what predecessor Harry S. Truman ordered. Crowds lined streets as Obama’s motorcade rolled past.

“I think it is very significant that this is the first time U.S president visit to Hiroshima,” Kenzo Kato, 37, an elementary school teacher from Yamaguchi, said through a translator. “I hope many people will think about the A-bomb.”

They wanted Obama to understand what happened there – that their lives changed following the deaths, the illnesses and damages left in the bomb’s wake. Years later, they are still suffering with diseases, medical bills and painful memories.

“I thought he might not be able to come,” Rikiya Murakami, 81, who worked at the agricultural cooperative in Iwat, said through a translator. “I’m grateful. I think it’s good. Hope for peace – we share the same everywhere.”

In his speech, Obama honored the victims and touted a world free of nuclear weapons. “That is a future we can choose,” he said. “A future in which Hiroshima and Nagasaki are known not as the dawn of atomic warfare but as the start of our own moral awakening.”

The visit comes seven years after Obama promised in a 2009 speech in Prague to take “concrete steps toward a world without nuclear weapons.” Yet critics said he has not fulfilled the promise that won him the Nobel Peace Prize.

“We applaud the president’s decision to honor the brutal lessons of Hiroshima,” said Derek Johnson, executive director of Global Zero, which advocates for the elimination of nuclear weapons. “But now, with just eight months left in office, the world needs more than words. President Obama must take urgent action to reduce the threat of nuclear weapons being used again.”

Obama has reduced the stockpile less than any other post-Cold War president and warhead dismantlement has declined on his watch, according to the Federation of American Scientists.

In a recent interview with Japanese TV, Obama acknowledged that he has made only “modest progress” in reducing the world’s nuclear risks

Other U.S. presidents had considered making the trek to Hiroshima over the years but decided against it, in part because of political sensitivities. President Jimmy Carter visited the Japanese city, but not until 1984, three years after he left office.

Secretary of State John Kerry became the highest-ranking administration official to visit the site when he attended a memorial ceremony in Hiroshima in April.