HO CHI MINH CITY, Vietnam — The Trump administration has told its senior diplomats in Vietnam not to take part in events marking the 50th anniversary of the end of the war.

Four U.S. officials who insisted on anonymity to describe sensitive diplomatic decision-making said Washington had recently directed senior diplomats — including Marc Knapper, the U.S. ambassador to Vietnam — to stay away from activities tied to the anniversary April 30.

That includes a hotel reception April 29 with senior government leaders and an elaborate parade the next day — gatherings hosted by Vietnam in Ho Chi Minh City, also known as Saigon, where the war ended with South Vietnam’s surrender.

Veterans returning to Vietnam have also been told they’re on their own, for public discussions they organize on war and reconciliation, and anniversary events. For many, it amounts to a sudden reversal after months of anticipation.

“I really don’t understand it,” said John Terzano, a founder of the Vietnam Veterans of America Foundation who served two tours in Vietnam and has attended anniversary events for decades. “As a person who has dedicated his life to reconciliation and marveled at how it’s grown over the last 20 years or so, this is really a missed opportunity.

“It really doesn’t require anything of the United States to just stand there,” Terzano added, in an interview after landing in Hanoi. “This is all ceremonial stuff. That’s what makes it sound crazy and disappointing.”

A half-dozen people with knowledge of the directive said it was not clear where it originated or why it had been issued.

April 30 is the 100th day of Trump’s second term. Some U.S. officials speculated that a Trump appointee or a State Department leader feared drawing attention away from that milestone with events that might highlight America’s defeat in a war that Trump managed to avoid.

In 1968, a year when 296,406 Americans were drafted into military service, Trump received a diagnosis of bone spurs in his heels that led to a medical exemption.

Regardless of the reasoning for Washington’s retreat from the 50th-anniversary events, it adds another blow to decades of painstaking diplomacy by Republican and Democratic administrations, which had sought to heal the war’s wounds and build a strategic partnership for countering China.

Trump had already frozen U.S. Agency for International Development money allocated for addressing the legacy of the war. Even after officials restored some of it, many programs — for finding missing soldiers and demining old battlefields, for example — are still struggling with layoffs and uncertainty.

The momentum of postwar bonding led in 2023 to a new level of strategic partnership between the two nations. And the work had been on track to expand, until Trump’s approach to the world, pugilistic and allergic to the acknowledgment of errors, strained relations.