Hiroshima & Nagasaki clouds Obama's visit to Japan

President Barack Obama touched down in Japan early Wednesday, kicking off a historic visit which will see him become the first incumbent US president to visit Hiroshima, the site of the first nuclear attack in history on August 6, 1945.

There is an air of anticipation around Japan, which is hosting the G7 Summit, but there has been no indication from Obama that the US government will "apologise" for dropping nuclear bombs on Hiroshima and Nagasaki.

140,000 people were killed in Hiroshima, while 74,000 perished in the second nuclear strike on the city of Nagasaki three days later.

Tens of thousands were killed by the after effects of the bombings in the years that followed.

Hiroshima mayor Kazumi Matsui has already demanded that Obama offer an apology for his country's actions during World War II, but for the survivors of the nuclear attack there's something much more significant that the US leader can do.

Nagasaki survivor Terumi Tanaka says, "He doesn't have to apologise if he is truly moved, feels remorse and understands what to do to eliminate nuclear weapons."

In a sentinment broadly echoed in Japan, Hiroshima survivor Toshiki Fujimori says he has no feeling of hate towards "America as a whole" but blames then-president Harry Truman for ordering the nuclear strikes.

A Japanese foreign ministry official told media, "The significance of President Obama's visit is that the US, the world's only nation to have used nuclear weapons, and Japan, the word's only nation to have been attacked with nuclear weapons, will express their strong determination to realise a nuclear-free world."

Obama plans to visit the Hiroshima memorial on May 27.

The historic visit will, however, not gloss over the recent murder of a Japanese woman in Okinawa in which the prime suspect is said to be a former American marine stationed on the island.

Okinawa hosts more than half of the 50,000 American troops based in Japan.

Locals have long been angry about Americans from the base committing crimes on the island.