How many US troops were in Vietnam?

President Johnson had already appointed General William C. Westmoreland to succeed Paul D. Harkins as Commander of MACV in June 1964. Under Westmoreland, the expansion of American troop strength in Vietnam took place. American forces rose from 16,000 during 1964 to more than 553,000 by 1969. With the U.S. decision to escalate its involvement, ANZUS Pact allies Australia and New Zealand agreed to contribute troops and material to the conflict. They were quickly joined by the Republic of Korea (second only to the Americans in troop strength), Thailand, and the Philippines. The U.S. paid for (through aid dollars) and logistically supplied all of the allied forces. Meanwhile, political affairs in Saigon were finally settling down (at least as far as the Americans were concerned}. On 14 February the most recent military junta, the National Leadership Committee, installed Air Vice-Marshal Nguyen Cao Ky as prime minister. In 1966, the junta selected General Nguyen Van Thieu to run for president with Ky on the ballot as the vice-presidential candidate in the 1967 election. The best thing that can be said about the election of 1967 was that it was held. Thieu and Ky were elected and would remain in office for the duration. In the presidential election of 1971, Thieu ran for the presidency unopposed. With the installation of the Thieu and Ky government (the Second Republic), the U.S. finally had a legitimate government in Saigon with which to deal.