As the Eisenhower administration began to commit the United States to an anti-communist advisory role in Vietnam in the 1950s, the Army Map Service (AMS) discovered that its comprehensive maps of Vietnam had become dated and showed signs of inaccuracy. Unfortunately, few sources existed to revise the existing topographic maps and aeronautical charts. AMS addressed the problem in 1956 by entering into a cooperative mapping agreement with the newly formed Republic of South Vietnam.