This day has been around since 2012. I searched on ‘Vietnam’ in thread titles, and there are zero threads about this out of 238 Vietnam threads.
Since 2017 this is an annual National Day here in the US.
Brief Hx, reverse chron (note, hx = history; according to Wikipedia)
►2017-03-28: President Trump signs the Vietnam War Veterans Recognition Act, for 29 March
►2012-03-29: President Obama proclaims March 29, 2012 as Vietnam Veterans Day
►1973-03-29: President Nixon; The last American combat troops leave Vietnam as per the Paris Peace Accords
►1962-03-29: President Kennedy; JCS finalizes instructions to MACV concerning “maximum discretion” and “minimum publicity” for US air operations in South Vietnam
National Vietnam War Veterans Day is a US holiday observed annually on March 29. It recognizes veterans who served in the US military during the Vietnam War.
►Ref: National Vietnam War Veterans Day - Wikipedia
►Retrieved 2020-03-28T0845U
Hx, more details
1962-03-29: President Kennedy — The Joints Chiefs of Staff finalized instructions to MACV (Military Assistance Command, Vietnam) concerning “maximum discretion” and “minimum publicity” for U.S. air operations in South Vietnam. If an enemy aircraft was shot down, MACV was instructed to remain silent unless it became necessary to contradict communist propaganda in which case MACV was to say that while on a routine training flight, an unidentified airplane initiated hostile action and was shot down. If a U.S. airplane was lost, MACV was instructed to say that the aircraft was on a routine orientation flight and the cause of the accident is being investigated. MACV was further instructed to ensure that all knowledgeable personnel were “instructed and rehearsed” with these rules.
►Ref: 1962 in the Vietnam War - Wikipedia
►Retrieved 2020-03-28T0907U
1973-03-29: President Nixon
The last American combat troops left Vietnam as per the Paris Peace Accords. The U.S. military command in South Vietnam, MACV ceased to exist. Fewer than 250 U.S. military personnel remained in Vietnam assigned to the U.S. Embassy in Saigon for advisory duties plus a few marines for protection of the Embassy. About 8,500 civilians working for the U.S. government remained in South Vietnam.
An official publication of North Vietnam summed up the pluses and minuses of the peace agreement. On the positive side for North Vietnam, the U.S. had ended its military operations in both South and North Vietnam and had begun to remove mines from coastal waters of North Vietnam. On the negative side, the cease fire had not been effective, although combat was not as intensive as before, and the U.S. continued to support South Vietnam by turning over its military bases and providing weapons and other military material to South Vietnam.
►Ref: 1973 in the Vietnam War - Wikipedia
►Retrieved 2020-03-28T0918U
2012-03-29: President Obama
On March 29, 2012, President Barack Obama proclaimed March 29, 2012, as Vietnam Veterans Day. The proclamation called “upon all Americans to observe this day with appropriate programs, ceremonies, and activities that commemorate the 50 year anniversary of the Vietnam War.”
►Ref: National Vietnam War Veterans Day - Wikipedia
►Retrieved 2020-03-28T0845U
2017-03-29: President Trump
On December 26, 2016, the Vietnam Veterans Day Coalition of States Council presented a letter to President Elect Donald Trump and Congressional leadership outlining the history and timeline of cause to establish March 29 as Vietnam War Veterans Day and requesting that it be one of the first legislations passed and signed into law during the 115 Congress.
On March 28, 2017, President Trump signed the Vietnam War Veterans Recognition Act of 2017. This act officially recognizes March 29 as National Vietnam War Veterans Day. The Act also includes the day among those days on which the US flag should especially be displayed.
►Ref: National Vietnam War Veterans Day - Wikipedia
►Retrieved 2020-03-28T0845U
For our veterans, specifically for those who served in the Vietnam War, I salute you. Especially if you were drafted. Welcome home.
(I was too young. My service, USMC, started in 1980. I enlisted; wasn’t drafted.)