John Kerry and other G7 foreign ministers on Monday were set to make a landmark visit to the memorial site for the world's first nuclear attack, as a US official ruled out an apology for the World War II atomic bombing that left 140,000 people dead.
Kerry is the first US secretary of state to visit Hiroshima and the highest-ranking administration official ever. In 2008, Nancy Pelosi, the then speaker of the House of Representatives and third in the line of presidential succession, also visited.
Kerry's trip comes as White House officials say President Barack Obama is considering stopping in the city late next month around the time of the Group of Seven summit to take place in another part of Japan.
Kerry's unprecedented visit to Hiroshima and speculation that Obama may also come have received wide media attention in Japan and even raised speculation over whether a US apology could be forthcoming.
Kerry and other officials, however, have sought to dispel that expectation.
"My visit to Hiroshima has a very special meaning about the strength of our relationship and the journey we have travelled together since the difficult time of the war," Kerry told Japanese foreign minister Fumio Kishida on Monday ahead of the visit to the memorial.
He added that the visit "is not about the past, it's about the present and the future".
Separately, a US official said flatly that Kerry would offer no formal apology.
"If you are asking whether the secretary of state came to Hiroshima to apologise, the answer is no," the State Department official, who asked not to be named, told reporters travelling with Kerry late Sunday.
The first American bomb on August 6, 1945, killed 140,000 people in Hiroshima, including survivors of the explosion who died afterwards from severe radiation exposure.
Three days later another blast killed some 74,000 people in Nagasaki. On August 15, then Emperor Hirohito announced Japan's surrender.
The issue of the bombings is a highly emotive one in both Japan and the United States.
Japan, as the only nation to experience a nuclear attack, emphasises the suffering its people endured. But while publicly calling for the eradication of nuclear weapons it has for decades been a close security ally of Washington under the protection of the US nuclear umbrella.
Many in the US, meanwhile, chafe at the suggestion of an apology, saying that Japan started the war with its attack on Pearl Harbor and argue that the atomic bombings hastened the war's end, thus preventing greater casualties.
Among other G7 foreign ministers set to visit the memorial are Britain's Philip Hammond and France's Jean-Marc Ayrault. It also marks the first time that top diplomats from the two nuclear-armed countries are visiting Hiroshima.
The group journey to the memorial comes as the ministers wrap up their final day of meetings with discussions focused on global hotspot issues including terrorism and other security threats as well as instability in the Middle East and elsewhere.