The trip comes amid warming ties between the countries as the US seeks to build relations with Pacific allies.
奥巴马此行起源于美越两国逐渐升温的双边关系，因为美国此前一直在寻求和太平洋盟友建立良好的双边关系。
Vietnam is keen for the US to lift an arms embargo that has been in place since 1984.
越南迫切希望美国能够解除自1984年以来的武器禁运。
Mr Obama will later fly to Japan for a G7 summit. He will also become the first US president to visit Hiroshima.
在结束对越南的访问后，奥巴马还会启程前往日本参加七国集团峰会。他还将是第一个访问广岛的美国总统。
While in Vietnam, Mr Obama is expected to meet dissidents and make the case for Vietnam to remove obstacles to the US-led Trans Pacific Partnership (TPP) free trade deal.
在访越期间，越南加入美国领导的跨太平洋伙伴关系（TPP）自由贸易协定一事也将被提上议程。奥巴马将和越南的反对派会面，并扫清越南加入TPP的障碍。
Ben Rhodes, Mr Obama’s deputy national security adviser, said before the visit that talks on removing the United States’ embargo on selling arms to Vietnam would be discussed.
在出访前，奥巴马的副国家安全顾问本·罗德表示说，奥巴马将会和越南讨论解除对越武器禁运的限制。
Doing so would allow Vietnam to bolster its defences at a time of territorial disputes with its neighbour China, which was unhappy with a partial lifting of the ban in 2014.
这一做法将给越南带来好处，使得其在和邻国中国发生领土纠纷时，可以提升自己的防御能力。美国在2014年对越南部分解除武器禁运的限制，此举曾引起中国不满。
However, White House officials indicated the ban would be lifted only if there was an improvement in human rights in Vietnam.
但是，有美国政府官员指出，只有越南的人权状况有所好转之后，才会解除对越武器禁运。
On Friday, Mr Obama will tour Hiroshima, where a US nuclear bomb was detonated in 1945, killing at least 140,000 people.
在本周五，奥巴马将会访问日本广岛。美国曾于1945年在广岛投放原子弹，造成至少14万人死亡。
In an interview with Japanese broadcaster NHK on Friday, Mr Obama said he would not apologise during his remarks in Hiroshima.
在上周五接受日本NHK电视台采访的时候，奥巴马表示在他于广岛讲话的时候，他将不会（就美国投放原子弹一事）道歉。
"It’s important to recognise that in the midst of war, leaders make all kinds of decisions, it’s a job of historians to ask questions and examine them," he said.
奥巴马说：“人们必须认识到，在战争中，领导人会做出各种各样的决策，而质疑和检验这些决策则是历史学家的工作了。”
"But I know, as somebody who’s now sat in this position for the last seven-and-a-half years, that every leader makes very difficult decisions, particularly during wartime."
“我在最近的七年半时间里担任了美国总统一职，所以我知道，每个领导人的决策都很艰难，尤其在发生战争的时候。”
