Looming over the President's visit -- which includes a stop in the Vietnamese capitol of Hanoi -- is the fact that Trump received multiple deferments during the Vietnam War. He also later compared his work and social life as a real estate developer in New York to the sacrifices made by American soldiers in the distant country.
It is unclear whether Trump will visit historic war sites in Da Nang, where he will attend his first meeting of the Asia-Pacific Economic Cooperation forum, or Hanoi, where he will meet with Vietnamese President Trần Đại Quang.
When asked directly whether Trump would visit the infamous Hỏa Lò Prison, nicknamed the Hanoi Hilton, a senior administration said that those decisions would be made later in the trip.
In his first remarks in Vietnam, Trump touted the current tone of US-Vietnamese relations.
"This city was once home to an American military base in a country where many Americans and Vietnamese lost their lives in a very bloody war," he said at the APEC CEO summit. "Today, we are no longer enemies, we are friends."
Later in the day, Trump met with a small group of Vietnam veterans and pledged that the United States would not rest until all soldiers missing in action in Vietnam are returned home.
Trump attended the private New York Military Academy in high school, but he avoided the draft through a series of education and health deferments.
After receiving four deferments due to education, Trump was diagnosed with bone spurs in his heels at the age of 22 in 1968, seven years before the Vietnam War ended.
The diagnosis earned him a 1-Y medical deferment, meaning he was barred from military service in the same year that roughly 300,000 troops were enlisted into the military.
Trump has defended the deferments in the past.
In a 2016 interview with The New York Times
, Trump said that a doctor "gave me a letter -- a very strong letter -- on the heels."
"Over a period of time, it healed up," he added.
And in a 2015 biography, Trump told Michael D'Antonio that the bone spurs were "not a big problem, but it was enough of a problem" that it made him unable to march long distances.
Trump's draft deferments became political issues during the 2016 election, especially after he attacked the family of a fallen solider who spoke at the Democratic National Convention.
But it was the comment from McCain, a member of Trump's own party, that seemed to deride Trump the most.
McCain, in an interview with CSPAN, appeared to take a swipe at Trump when he criticized people from "the highest income level" who avoided the draft by finding a doctor who "would say that they had a bone spur."
McCain never mentions Trump by name in the interview, but the President's deferment because of a bone spur is widely known and the President's family was well off at the time. McCain, who said he wasn't talking about Trump, added later that he didn't believe Trump was a draft dodger.
Rick Weidman, executive director of policy and government affairs at the Vietnam Veterans of America, told CNN before Trump's trip that little can be gained from the President re-litigating his decisions during the Vietnam War while in the region.
"What happened then, happened then and nobody is going to be able to change it," said Weidman, who served as a medical corpsman during the war. "And he now has the power to change things going forward."
Weidman said he hopes Trump addresses the still-evident scars of the war while in Vietnam, including joint projects by the United States and Vietnamese to identify soldiers missing in action. The United States, according to the group, still has 1,602 soldiers missing in action in Vietnam.
His own 'Vietnam'
Years after avoiding the draft, Trump had made light of service in the Vietnam War by comparing it to both his professional and social endeavors and by deriding those who have served.
Trump, known for being a fixture in the New York tabloids at the time, agreed with Howard Stern in 1998 when the shock jock suggested that avoiding sexually transmitted diseases in New York was "your Vietnam."
"It's Vietnam," Trump said. "It is very dangerous. So I'm very, very careful."
Earlier in the interview, first reported by CNN's KFile
, Trump said he was "getting the Congressional Medal of Honor" because of his ability to stay alive with "screwing a lot of women."
And Trump kicked off his feud with McCain, a fight that has lasted years, but stating in 2015 that McCain was not a war hero because he was captured during the Vietnam War.
"He is not a war hero," Trump said. "He is a war hero because he was captured. I like people that weren't captured, OK? I hate to tell you. He is a war hero because he was captured."
McCain served in the Navy until 1981, where he was famously a prisoner of war at Hỏa Lò Prison. McCain declined early release during his over five years in captivity, a benefit that would have been granted to him because his father was an admiral in the Navy.
Focus on trade, security
His own Vietnam history aside, Trump and his cadre of traveling aides and advisers will look to use the President's stop in Vietnam to drive home his call for free and fair trade.
In Vietnam, said a senior administration official, Trump will work "to remove unfair trade barriers" and "enhance our economic dialogue."
"We think Vietnam is an excellent partner in the region and that there's a lot of opportunity for us to engage in finding ways to work together bilaterally and regionally to promote growth throughout the region," the official said.
But Trump's focus on trade in Vietnam will likely come with possibly painful discussions on the Trans-Pacific Partnership, a massive trade agreement for the region that Trump withdrew from early in his administration.
Vietnam, one of the smallest countries that signed onto the TPP, stood to gain much and was drawn to the deal, in part, because of the access to the United States it would have provided.
In the aftermath of the United States' withdrawal, countries in the region have pressed forward with what is being called TPP 2.0 and leaders in Vietnam have backed the plan.
Though relations between Trump and Vietnam have been positive since he took power in January -- Vietnamese Prime Minister Nguyen Xuan Phuc was the first Southeast Asian leader to visit the White House under Trump -- it remains to be seen whether Vietnamese leaders will harbor some animus towards the United States for leaving the deal.
Amy Searight, director of the Southeast Asia Program at the Center for Strategic and International Studies, told reporters "the United States withdrawal from TPP has had serious implications for Vietnam."