Why the US's and Vietnam's militaries became unlikely comrades, and how their relationship survived Trump

• As US ambassador to Vietnam in 2017, Ted Osius presided over the first major handover of US military hardware to Vietnam.
• Since then, the militaries have only grown closer as the US seeks to help Vietnam stand up to China.

When Ted Osius was a boy, the United States was mired in its bloody invasion of Vietnam.

How far the two governments have come.

In more recent years, as US ambassador to the country, Osius presided over the first major handover of American military hardware to Vietnam's communist government. (It was a fleet of high-tech patrol boats called Metal Sharks.)

That was in 2017. Since then, the two countries' militaries have only grown closer. It is now routine for US naval vessels (including aircraft carriers) to visit Vietnam — and for the two armed forces to train together and share tactics.

It's all part of a US-led strategy to help Vietnam's navy stand up to China, namely in the South China Sea, the largest sea body on Earth, which is now flooded with Chinese warships and militarized island bases.

But how far will the US go to make a darling of Vietnam's military?

The World's Southeast Asia correspondent Patrick Winn asked former Ambassador Osius, who served in Hanoi from 2014 to 2017. He is the author of the memoir "Nothing is Impossible: America's Reconciliation with Vietnam."

Patrick Winn: During your term, the US started giving military hardware to the communist government of Vietnam. And now, US warships and allies visit frequently. What does Vietnam get out of these military relations?

Ted Osius: Well, Vietnam faces a very formidable neighbor. Facing this situation with its northern neighbor, China, Vietnam has looked for friends. And the United States is prepared to be a friend. We haven't talked about being allies, never in a serious way. But we've become partners.

Winn: Can you briefly lay out the reasons Vietnam is historically wary of China?

Osius: The Vietnamese have been fighting the Chinese for thousands of years. They're going to resist domination, particularly by China. They'll resist domination by any foreign power. They certainly resisted us. They resisted the French. But it's in their DNA to resist the Chinese. Every village in Vietnam has streets named Bà Triệu and Hai Bà Trưng … and other Vietnamese heroes who fought the Chinese. This is part of who they are.

Winn: How often did you encounter high-ranking communist officials who were uneasy seeing the US get closer and closer to Vietnam? Or maybe worrying they're being used as a proxy against China?

Osius: Oh, quite often! I encountered loads of people who were quite suspicious of US motives. Maybe just one short story to illustrate: I hosted Defense Secretary Ash Carter when he visited Hanoi. And we went to meet with Defense Minister [Phùng Quang] Thanh. We had a lovely dinner. We drank lots of wine. It was very jovial. And at a certain point, Ash Carter said, "Mr. Minister, how did you meet your wife?" He said, "Well, she picked shrapnel out of my hip." Now the reason she picked shrapnel out of his hip is because Americans put it there. And then Minister Thanh said, "You know, if we'd had a dinner like this back then, there never would have been a war." But it took a lot of evenings like that, a lot of trust building, before people who had fought against us could consider us their friends.

Winn: That brings us to a very recent visit by Vice President Kamala Harris to Vietnam, where she called China "bullies" and said we should work together to increase pressure on Beijing. But a naval standoff with China — that costs a fortune in military spending. What does the average US citizen, living 8,000 miles away, actually get out of that?

Osius: Well, I don't think the US citizen 8,000 miles away cares about who is in control of which islands in the South China Sea. What we have an interest in is freedom of navigation. The South China Sea is an area where half the world's seaborne cargo passes through every year. It's a very busy thoroughfare, an international waterway. And for something like 250 years, the United States has stood very solidly for freedom of navigation. It's critical to US security and it's critical to the security of our friends and allies. So, the idea that the Chinese could draw a line around this international waterway and say, "Oh, this is ours. You have to ask our permission to come through." That is anathema to the United States.

Winn: You also served under President Donald Trump. And you were in the room right before he met the prime minister of Vietnam at the time: Nguyễn Xuân Phúc. And Trump starts making racist jokes about his name, Phúc. Can you describe how you were feeling at the time?

Osius: Well, I felt really bad. It was a real contrast for me. When I'd been in the Oval Office with Barack Obama, he'd shown great respect to his Vietnamese visitor. He'd spent hours preparing for the meeting and the meeting changed the course of US-Vietnam relations. It was hugely impactful because he did the simple thing, which is to show respect. We couldn't get Donald Trump to spend five minutes preparing for this meeting. We had given him a little piece of paper with a few checklist items. He wouldn't read it. And when we tried to brief him, he made this racist joke, and clearly wasn't at all interested in being briefed. I tried to interest his son-in-law, Jared Kushner, in the substance of the meeting. That failed equally spectacularly. That meeting wasn't a catastrophe. But the reason it wasn't is because the Vietnamese were determined to put up with whatever — because they wanted a partnership with the United States.

Winn: Well, it ultimately doesn't sound like the Trump years did major damage to the US-Vietnam friendship. Why do you think this is? Is this a military-driven relationship that goes beyond whoever is in the White House?

Osius: It's very interesting to me that it wasn't. I thought that when we withdrew from the Trans-Pacific Partnership trade agreement, and left the Vietnamese kind of holding the bag, that there would be a lot of anger. And there wasn't. There was a determination made, right at the beginning, that [Vietnam would] keep going. To keep improving this relationship, you know? "So, there's a different president in the White House? We're going to figure out how to work with that new president." And they did. They were very practical about it. The Vietnamese have continued to be very practical. Now, they're marching forward with the Biden administration, finding ways we can enhance collaboration in health, climate change and, ideally, in trade as well.

Winn: In the US, there's a lot of drama and celebrity-style attention toward politicians. In Vietnam, it's very different. How would you describe the difference?

Osius: A lot of things in Vietnam happen behind the scenes. There is not a lot of flash on the part of Vietnamese leaders. … They tend not to get a lot of headlines for their work. They tend to do things quietly, effectively, behind the scenes. So, there would be times it was a little hard to tell what was going on in the politburo. Where, of course, in the United States, everything is out there, warts and all. These two styles … in some fields, caused a challenge. For example, with human rights. Barack Obama explained to Nguyễn Phú Trọng [an official who is now leader of Vietnam's Communist Party] when he visited, we are who we are, warts and all. We're constantly striving for a more-perfect union … we make our mistakes and we make them in public.We really did look at human rights in a very different way. That was something that was really hard to reconcile. I spent a lot of time on that, working really hard to see what we could do. I don't know that we made as much progress as I would have liked.

This interview has been lightly edited for length and clarity.