Prime Minister Shinzo Abe, in a statement marking the 70th anniversary of World War II's end, acknowledged Japan had inflicted "immeasurable damage and suffering" on innocent people but said generations not involved in the conflict should not be burdened with continued apologies.
Abe's remarks are being closely watched abroad for whether the conservative leader is watering down past apologies.
The legacy of the war still haunts relations with China and South Korea, which suffered under Japan's sometimes brutal occupation and colonial rule before Tokyo's defeat in 1945.
Beijing and Seoul have made clear that they want Abe, seen by many as a revisionist who wants to play down the dark side of Japan's wartime past, to stick to a 1995 "heartfelt apology" by then-premier Tomiichi Murayama for suffering caused by Tokyo's "colonial rule and aggression". The United States also wants Abe to avoid inflaming tensions in the region.
Abe met U.S. ambassador to Japan Caroline Kennedy on Monday.
Abe's statement comes as he pushes for a more robust defense policy through measures domestic critics say violate Japan's pacifist constitution. Public doubts about the bills have triggered a slide in Abe's ratings to below 40 percent.
Washington has welcomed the changes, which Abe says are needed to meet new challenges, including a more assertive China.