Photo gallery: Obama at Hiroshima

Presdent Obama shakes hands with Japanese Prime Minister Shinzo Abe after laying a wreath in front of the cenotaph to offer a prayer for victims of the atomic bombing in 1945 at Hiroshima Peace Memorial Park in Hiroshima on May 27, 2016.

Presdent Obama puts his hand on the shoulder of Japanese Prime Minister Shinzo Abe after laying a wreath in front of a cenotaph to offer a prayer for victims of the atomic bombing in 1945 at the Hiroshima Peace Memorial Park in Hiroshima on May 27, 2016.

Presdent Obama stands with Japanese Prime Minister Shinzo Abe in front of the cenotaph during his visit to the Hiroshima Peace Memorial Park in Hiroshima on May 27, 2016.

President Obama, accompanied by Japanese Prime Minister Shinzo Abe, right, leaves the Hiroshima Peace Memorial Park after laying a wreath in Hiroshima, Japan, on May 27, 2016.

People try to get a glimpse of the wreath laid by US President Obama at the Hiroshima Peace Memorial park cenotaph in Hiroshima on May 27, 2016.

The wreath placed by US President Barack Obama is displayed in front of the cenotoph in the Peace Momorial park in Hiroshima on May 27, 2016.

A woman wearing a stars and stripes hat waits for the arrival of President Obama around Hiroshima Peace Memorial Park in Hiroshima, Hiroshima Prefecture, Japan, on May 27, 2016.

President Obama lays wreaths at the cenotaph at Hiroshima Peace Memorial Park in Hiroshima, western Japan, on May 27, 2016.

President Obama visits the Hiroshima Peace Memorial Park on May 27, 2016 in Hiroshima, Japan.

U.S. President Obama, left, shakes hands with Japanese Prime Minister Shinzo Abe after laying a wreath at Hiroshima Peace Memorial Park in Hiroshima, western Japan, on May 27, 2016.

U.S. President Obama stands after laying a wreath at the Hiroshima Peace Memorial Park in Hiroshima, western, Japan, on May 27, 2016.