During Holt's term in office, the
Vietnam War was the dominant foreign policy issue. The Holt government significantly increased its military involvement in the conflict and Holt was a strong advocate of US policy in the region. Holt also forged a close relationship with
U.S. President Lyndon B. Johnson — he visited Washington in mid-1966 and Johnson visited Australia in October that year, the first time a serving American president had visited Australia.
Whilst Holt stated that his friendship with Johnson was reflected in the strong relationship between Australia and the USA, former Australian diplomat and foreign affairs expert
Alan Renouf was more cynical in his assessment of the situation. In the chapter on Vietnam in
The Frightened Country, his 1979 book on Australian foreign policy, Renouf bluntly suggests that Holt was in effect "seduced" by Johnson, and he notes that the Holt government was criticized for not doing enough and was repeatedly pressured by the Johnson administration to increase its troop commitment in Vietnam.
On taking office, Holt declared that Australia had no intention of increasing its commitment to the
Vietnam War, but a month later, in March 1966, he announced that Australia would treble its troop commitment to 4,500, including 1,500
National Service conscripts, creating a single independent Australian task force based at
Nui Dat.
Two months later, in May, Holt announced the death of the first National Service conscript in Vietnam, Private
Errol Wayne Noack, aged 21. Just before his disappearance, Holt approved a further increase in troop numbers, committing a third battalion to the conflict — a decision that was subsequently reversed by his successor,
John Gorton.
On a visit to the USA in late June, 1966, Holt gave a speech in Washington in the presence of President Lyndon B. Johnson. Reported in
The Australian on
1 July 1966, Holt's speech concluded with a remark which has come to be seen as encapsulating his unquestioning support for Johnson, for America's Vietnam policy and for continued Australian military involvement in the conflict:
:"You have in us not merely an understanding friend but one staunch in the belief of the need for our presence in Vietnam.
:"We are not there because of our friendship, we are there because, like you, we believe it is right to be there and, like you, we shall stay there as long as it seems necessary to achieve the purposes of the South Vietnamese Government and the purposes that we join in formulating and progressing together.
:"And so, sir, in the lonelier and perhaps even more disheartening moments which come to any national leader, I hope there will be a corner of your mind and heart which takes cheer from the fact that you have an admiring friend, a staunch friend that will be all the way with LBJ."
Following his visit to Washington, Holt went on to London and in a speech there given on
7 July he was sharply critical of the UK, France and other US allies that had refused to commit troops to the Vietnam conflict.
On
20 October 1966, President Johnson arrived in Australia at Holt's invitation for a three-day state visit, the first to Australia by a serving U.S. President. The tour marked the first major anti-war demonstrations staged in Australia. In Sydney, protesters lay down in front of the car carrying Johnson and the
Premier of New South Wales, Robert Askin (prompting Askin's notorious order to "Run over the bastards"). In Melbourne, a crowd estimated at 750,000 turned out to welcome Johnson, although a vocal anti-war contingent demonstrated against the visit by throwing paint bombs at Johnson's car and chanting "LBJ, LBJ, how many kids did you kill today?".
In December, Australia signed an agreement with the United States that would allow the U.S. to establish a communications facility at
Pine Gap in the
Northern Territory. On
20 December 1966, Holt announced that Australia's military force in Vietnam was to be increased again to 6,300 troops, plus an additional twelve tanks, two minesweepers and eight bombers.
