Barack Obama will become the first U.S. president to visit Hiroshima in Japan later this month, but he will not apologize for the United States' dropping of an atomic bomb on the city at the end of World War Two, the White House said on Tuesday. [url=http://www.reuters.com/article/us-usa-japan-obama-idUSKCN0Y11KC]http://www.reuters.com/article/us-usa-japan-obama-idUSKCN0Y11KC[/url]