US President Barack Obama began his official tour of Asia on 23 May and is expected to tour Vietnam for three days and later travel to Japan to attend the G7 summit in Ise Shima. He will also become the first US president to visit Hiroshima after the 1945 bombing that killed 140,000 people.
His visit follows the trip of US Secretary of State John Kerry, who paid tributes to the victims of the bombings at the Hiroshima peace memorial park.
In an interview with Japanese news channel NHK, Obama said that he will not apologise for the atomic bombings of Hiroshima and Nagasaki. He said, "I think that it's important to recognise that in the midst of war, leaders make all kinds of decisions.
He added, "It's a job of historians to ask questions and examine them, but I know as somebody who has now sat in this position for the last seven and a half years, that every leader makes very difficult decisions, particularly during war time."
However, some critics have argued that even as more than 70 years have passed since the bombings, emotions are still raw and an apology is expected.
In Japan, a National A-bomb survivors group has urged Obama to apologise to the victims of the nuclear attack and to acknowledge that usage of the bomb was against international laws, USA Today reported.
Terumi Tanaka, secretary general of the Japan Confederation of A-Bomb and H-bomb Sufferers Organisations, said Obama should at least apologise in memory of the victims.
Meanwhile, Japanese Prime Minister Shinzo Abe and other local leaders have expressed that "no apology is needed".
The US had dropped one bomb each in Hiroshima and Nagasaki on 6 and 9 August 1945, respectively. Around 80,000 lives perished in the Nagasaki attack.
Further, Obama said that the current relationship between the two countries is what matters and that the two need to strengthen ties. "I think it is also a happy story about how former adversaries came together to become one of the closest partnerships and closest allies in the world."
He also spoke about the effects of wars on people. He was was quoted as saying: "Since I only have a few months left in the office, I thought it was a good time for me to reflect on the nature of war. Part of my goal is to recognize that innocent people caught in war can suffer tremendously."
"And that's not just the thing of the past. That is happening today in many parts of the world."