U.S. Ambassador to Japan John Roos will attend the annual ceremony Tuesday in Hiroshima to commemorate the 68th anniversary of the 1945 U.S. atomic bombing of the city, the U.S. Embassy in Tokyo said Sunday.

It would be Roos' third time representing the United States at the Hiroshima Peace Memorial Ceremony and his last as ambassador.

The U.S. government is also arranging for Roos to take part in the Nagasaki ceremony on Friday, as he did last year, sources close to Japan-U.S. relations said.

Roos became the first U.S. ambassador to Japan to attend the Hiroshima ceremony in 2010, which was the 65th anniversary of the bombing. He attended the Nagasaki ceremony last year for the first time.

Behind the attendances is U.S. President Barack Obama's desire to eradicate nuclear weapons worldwide.

In the statement announcing Roos' attendance at the ceremony, the embassy said the United States "looks forward to continuing to work with Japan to advance President Obama's goal of realizing a world without nuclear weapons."