On 3 September 1967, Nguyễn Văn Thiệu was elected president of the Republic of Vietnam (RVN). Born in Ninh Thuận Province in November 1924 (later changing his birthday to 5 April 1923), Thiệu joined the French-supported Vietnam National Army in 1948. As a member of the South Vietnamese army in the fight against the communist North, Thiệu rose in rank. Thiệu, a Catholic supporter of the previous President Ngô Đình Diệm, became President through winning the ballot vote as expected. However, his inauguration arose partly because the country’s most popular military figure, General Dương Văn Minh, had been disqualified as a candidate on a technicality. Thiệu ended up with a surprisingly modest 35 per cent plurality vote (with civilian candidate Trương Đình Dzu polling 17 per cent to finish second). Thiệu’s government only lasted two years after the US withdrawal. Thiệu was forced to flee Vietnam in 1975.
When Nguyễn Văn Thiệu succeeded Nguyễn Cao Kỳ as president of the RVN in November 1967, Kỳ was made vice-president. To allow the two running-mates to work together, their fellow officers agreed to have a military body controlled by Kỳ shape policy behind the scenes. The election was rigged to ensure that Thiệu and Kỳ’s military ticket would win, and strong executive powers meant that a military junta still ruled. Kỳ was seen as a staunch authoritarian and a junta politician, developing a perpetual struggle for influence in the junta against the outspoken General Nguyễn Chánh Thi.
However, behind the scenes, there was a fierce rivalry between Nguyễn Văn Thiệu and Nguyễn Cao Kỳ that left Kỳ marginalized. In the aftermath of the Tết Offensive, Thiệu enforced martial law and used the situation to consolidate his personal power. Kỳ’s supporters in the military and the administration were quickly removed from power, arrested or exiled, ending any hopes of Kỳ exerting any power through the Southern Military Command or elsewhere. Alienated from Thiệu, Kỳ intended to oppose him in the 1971 elections, but Thiệu introduced laws to stop most of his rivals from running. Realizing that the poll would be rigged, Kỳ withdrew from politics. Thiệu ran unopposed and took 94 per cent of the vote in 1971.
In the same month, US General William C. Westmoreland ordered the fortification of Khe Sanh Combat Base in Quảng Trị Province. In 1967, after the first year of the Marine deployment to Khe Sanh in 1966, the People’s Army of Vietnam (PAVN) had infiltrated an estimated 62,000 men into South Vietnam. At the end of 1967, another 101,000 PAVN soldiers came down the Ho Chi Minh Trail and entered South Vietnam.
General Westmoreland wanted US Marines to curtail PAVN infiltration into South Vietnam along the system of trails throughout the Ho Chi Minh Trail. But, like previous military units stationed at the base before them, the US Marines failed to halt or even slow the flow of PAVN soldiers and supplies pouring into South Vietnam due to the adverse weather conditions and tough terrain.
Despite the inability of US Marines to do anything about PAVN infiltration, Westmoreland kept Marines at Khe Sanh. Westmoreland believed the base and its troops fulfilled important military objectives, most notably to serve as a patrol base blocking and harassing PAVN infiltration from Laos, providing an airstrip for reconnaissance to survey the Ho Chi Minh Trail and an anchor for the defences south of the Demilitarised Zone. Perhaps most importantly, Westmoreland wanted the base occupied in the event President Johnson authorized a cross-border invasion of Laos to cut the Ho Chi Minh Trail. If Johnson gave the order to go into Laos, the United States would need Khe Sanh as a staging ground.