Prime Minister Shinzo Abe's handling of wartime historical issues will be closely watched on the 70th anniversary of the end of World War II later this year, a recent U.S. congressional report said.

"International audiences will be watching closely on how Abe handles the upcoming commemorations," the U.S. Congressional Research Service report said, apparently reflecting general concern in Washington about fresh tension between Japan and its neighbors.

With the anniversary approaching in August "there is likely to be increased attention to the historical issues that have dogged Japan's relationship with its neighbors," said the report, titled "Japan-U.S. Relations: Issues for Congress" and dated Tuesday.