Obama on Friday became the first sitting USA president to visit the site of the world's first atomic bomb attack, bringing global attention both to survivors and to his unfulfilled vision of a world without nuclear weapons.
In a solemn ceremony on a sun-drenched afternoon, Mr. Obama and Japanese Prime Minister Shinzo Abe placed wreaths before the cenotaph, a simple arched stone monument at Hiroshima's Peace Memorial Park.
Barack Obama is the first sitting US president to visit the hallowed ground of Hiroshima, site of the world's first atomic bomb attack.
"We must have the courage to escape the logic of fear and pursue a world without them", Obama said of nuclear weapons.
Obama also met the sprightly Sunao Tsuboi, a 91-year-old who suffered serious burns in the blast and subsequently developed cancer.
"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.
In his speech, Obama honored the victims and spoke of the horrors of war, but stopped short of an apology for the USA bombing that led to the surrender of Japan and the end of World War II.
A majority of Americans see the bombings as having been necessary to end the war and save lives, although some historians question that view. His compassion and dignity will be welcome to the remaining survivors that still bear witness to those awful and unimaginable days in August 1945 when the United States unleashed atomic bombs on the cities of Hiroshima and Nagasaki.
In a brief visit to the museum at the peace park, Obama visited a display about a young girl who survived the bombing but died several years later of leukemia. On Friday, the president laid a wreath at the city's Peace Memorial Park, shook hands with survivors of the attack, and called on mankind to bring its moral progress up to speed with its technological prowess. Or, as he said in his speech, the bombing here should not be seen as "the dawn of immoral warfare but as the start of our own awakening". Obama is the first sitting USA president to ever visit the city. His call to pursue the world without nuclear weapons - echoing the sentiments of his Prague speech in 2009 - is important.
Obama's trip provides a coda eight months before he steps down and nearly five years after he announced Washington's "pivot" to Asia, a foreign policy strategy that has been overshadowed by emerging security threats from the Middle East and Russian Federation.
"We welcome President Obama", said 80-year-old Toshiyuki Kawamoto.
However, some argue that the Obama administration's "modernization" of the American nuclear arsenal has actually made it more likely that the weapons will be used in the future.
The announcement of the visit to Hiroshima reopened debates on the decision to attack Hiroshima and Nagasaki in the closing days of World War II.
Sherman Gillums Jr., a Marine veteran and executive director of Paralyzed Veterans of America, described Obama's visits to Vietnam and Hiroshima as "bittersweet for many, particularly ahead of Memorial Day".
The president evoked the horrors of the war to lay out his vision of a world without nuclear weapons.
Critics argue that by not apologizing, Obama will allow Japan to stick to the narrative that paints it as a victim.
"We have known the agony of war".
The president says his visit is a testament to how even the most painful divides can be bridged. In the two-day summit, the G7 leaders discussed the pressing global issues including counter-terrorism, energy policy, and sustainable development.
While some in Japan feel the attack was a war crime because it targeted civilians, many Americans believe it hastened the end of a bloody conflict, and ultimately saved lives.
"The president gestured as if he was going to give me a hug, so we hugged", Mr. Mori said. "I want him to understand our sufferings".