From: NY TIMES - Vietnam’s Eternal Flames: The Zippo as Much More Than a Keepsake
from wikipedia, like someone mentioned earlier they were all air bases but are situated along the coast... hence the "you can surf later" embroidery
During the Vietnam War, Vũng Tàu was home to the Australian Army and American support units, and was a popular spot for in-country R&R for U.S. combat troops. After the war, Vũng Tàu was a common launching place for the Vietnamese Boat People fleeing the communists. Vung Tau Army Airfield (VTAA) was the home of two U.S. Caribou squadrons (approx. 16 planes each) from 1964 until mid 1970.
During the Vietnam War, the city was home to a major air base that was used by both the South Vietnamese and United States air forces. The base was considered one of the world's busiest airports during the war. reaching an average of 2,595 air traffic operations daily, more than any airport in the world at that time. The final U.S. ground combat operations in Vietnam ceased on 13 August 1972, when a residual force of the 196th Light Infantry Brigade stood down in Đà Nẵng. B Battery 3rd Battalion, 82nd Field Artillery Regiment fired the final U.S. artillery round and the 3rd Battalion, 21st Infantry Regiment finished their final patrols. This residual force was known as "Operation Gimlet".
When Cam Ranh Bay used to be an important naval base, Nha Trang Airport was the main airport of the city. This airport was used by the United States Air Force and South Vietnam Air Force during the Vietnam War. Nha Trang is well known for its pristine beaches and excellent scuba diving and is fast becoming a popular destination for international tourists, attracting large numbers of backpackers as well as more affluent travelers on the Southeast Asia circuit. It is already very popular with Vietnamese tourists. Nha Trang Bay is widely considered as amongst the world's most beautiful bays.