The trip will offer an opportunity to solidify his promised pivot of American policy toward Asia and deepen economic and security ties with an increasingly important regional player.

But for the United States’ Vietnam war veterans, a presidential trip to the country where many of them lost their youth, innocence and some of their closest friends is weighted with powerful emotions and never-ending debates about that war’s consequences.

One of the stumbling blocks between the two nations is the continuing belief by some in the United States that there may still be captive American soldiers held there, the article said.

Mr. Obama is unlikely to focus as much on combat deaths during his trip as President Bill Clinton did when he visited in 2000. Mr. Obama is more likely to hail cooperation between the two countries to clean up the remnants of Agent Orange, one of the wartime issues still important to Vietnam.

In the article, Gardiner Harris also talked about Senator John McCain's efforts to help normalize relations between Vietnam and the United States.

Those efforts long ago helped Mr. McCain put the worst of the war and his captivity behind him, so he is unlikely to be moved by the photos of Mr. Obama’s visits, it said.