The Japanese survivors on Monday visited a museum exhibiting the aircraft, named the Enola Gay, on a trip that has jarred raw US emotions over Japan's wartime role.
Holding pictures of hideously burned victims of the blast, six survivors and about 50 peace activists visited the new museum in Chantilly, Virginia, where the shiny, four-engined Boeing B-29 Superfortress has just gone on display.
Two men were arrested after a bottle of red paint, meant to symbolise blood, was thrown, denting a panel on one side of the plane, which is parked in the new annex to the Smithsonian's National Air and Space Museum.
One demonstrator was charged with destruction of property, the other faces loitering charges, police said.
"This is the second time I have seen the Enola Gay," said Hiroshima survivor Minoru Nishino, 71, who was two kilometres from the epicentre of the blast, and still bears scars.
"This is the second time I have seen the Enola Gay. The first time was on 6 August, 1945, when I saw it flying high in the sky. When I saw it today, I was overcome by anger"
"The first time was on 6 August, 1945, when I saw it flying high in the sky. When I saw the Enola Gay today, I was overcome by anger."
Another survivor, Tamiko Tomonaga, 74, said she had travelled from Japan in memory of the dead.
But their act of remembrance next to the plane was too much for some museum visitors who angrily shouted, "Remember Pearl Harbor" and "What about the Nanjing massacre?" referring to actions of imperial Japanese forces.
"My Dad fought in the war - go home" shouted another man.
Fifty-eight years after the Hiroshima bombing, and a second atom bomb strike a few days later on Nagasaki, opinion here on the first nuclear strikes is still sharply divided.
Opponents argue the action, which killed up to 230,000 people - if those who died from radiation sickeness are included, was nothing short of a war crime.
However, some historians contend that despite the horror, the bombings shortened the war with Japan, saving untold lives.
Both viewpoints vied for prominence at the museum, located under the flightpath of Dulles international airport and which also houses a retired Air France Concorde and a space shuttle prototype.
Survivors are disappointed the Enola Gay is being displayed with no reference to casualty figures at Hiroshima.
"We would not mind the plane going on display if they showed the tragedy they caused," said Tomonaga, a Red Cross nurse at the time of the bombing.
Survivor Tamiko Tomonaga wants
the death toll to be displayed
The Enola Gay bears a label describing it as the "most sophisticated propeller-driven bomber of World War II".
The text mentions the technological prowess of the aircraft and how it "found its niche on the other side of the globe".
"On 6 August, 1945, this Martin-built, B-29-45-MO dropped the first atomic weapon used in combat on Hiroshima, Japan."
Remembering the dead
One angry onlooker who refused to give his name defended the decision not to give casualty figures.
"They (Japan) started the war by bombing our servicemen in Pearl Harbor, they should go and stand on the deck of the Arizona," he said, referring to a US ship sunk in 1941 that drew the United States into the war and which is now a memorial.
Another visitor to the museum, Joe Lassals, said, "I am thinking of all the American soldiers who were killed - why don't they remember them?"
The museum's director, retired general John Dailey, has resisted groups who want the death toll from the Hiroshima bombings included.
"We don't do it for other airplanes," he said. "From a consistency standpoint, we focus on the technical aspects."