The Vietnam War was a war fought in the eponymous nation. The United States participated.
Due to President Lyndon Johnson's pursuit of the Vietnam War, he was reviled by the counterculture movement in the United States. (PROSE: Wonderland)
In the 1960s, the Fifth Doctor, Nyssa, Wilton, Mulberry and Floyd visited Vietnam during the war and met Major Alice Hunniford. (AUDIO: Renaissance of the Daleks)
In 1965, the Latter-Day Pantheon decided to end the Vietnam War, but they were stopped by the US Army before they could finish with their plan. (PROSE: Salvation)
Igrix intended to stop the Vietnam War in 1968. (COMIC: The Love Invasion)
On 24 December 1969, the Third Doctor and Sarah Jane Smith visited Saigon in Vietnam during the Christmas ceasefire. (PROSE: Interesting Times)
River Song noted President Richard Nixon's involvement in Watergate and the Vietnam War before adding that there was "some good stuff too." (TV: The Impossible Astronaut)
The war ended on 23 February 1973, with no clear victor. The American soldiers who returned from Vietnam were met with contempt by the American public. (PROSE: Nuclear Time)