Japan's Prime Minister Shinzo Abe visited the U.S. naval base at Pearl Harbor. Japan's attack on the base in 1941 led to the USA joining World War II. Mr Abe did not apologize for the attack. He offered his "sincere" condolences to those who lost their lives. Mr Abe also said: "We must never repeat the horrors of war again. This is the serious vow the people of Japan have taken." President Obama welcomed Mr Abe, "in the spirit of friendship".
A total of 353 Japanese planes attacked Pearl Harbor, killing 2,403 people. The attack also damaged or destroyed 19 US warships. Mr Abe is the first Japanese leader to visit a special memorial there. He spoke about the US helping Japan after WWII. He said after the war, "Japan was a nation in burnt-out ruins as far as the eye could see, suffering miserable poverty" and the USA sent food and clothes. He said the two countries had an "alliance of hope".