This was instituted in 1965 to recognise service in Vietnam, Laos, Cambodia or Thailand in the period 1965-1973.

Awarded to all members of the Armed Forces of the United States serving in Vietnam and contiguous waters or airspace thereover, between 3 July 1965 and 28 March 1973. Members of the Armed Forces of the United States in Thailand, Laos, or Cambodia, or the airspace thereover, during the same period and serving in direct support of operations in Vietnam are also eligible for this award. To be eligible for award of the medal, individual must have:

1. been attached to or regularly served for one or more days with an organisation participating in or directly supporting military operations; or
2. been attached to or regularly served for one or more days aboard a naval vessel directly supporting military operations; or
3. actually participated as a crewmember in one or more aerial flights into airspace above Vietnam and contiguous waters directly supporting military operations; or
4. served on temporary duty for 30 consecutive days or 60 non-consecutive days in Vietnam or contiguous areas, except that the time limit may be waived for personnel participating in actual combat operations.

Individuals who qualified for the Armed Forces Expeditionary Medal for service in Vietnam between 1 July 1958 and 3 July 1965 also qualified for the medal. Upon request, the individual may be awarded the Vietnam Service Medal in lieu of the Armed Forces Expeditionary Medal. In such instances, the Armed Forces Expeditionary Medal was deleted from the list of authorised medals in the individual’s personnel records. No one is entitled to both awards for Vietnam Service.