Under the terms of the 1954 Republic of Korea-United States of America Mutual Defense Treaty, the United States and South Korea agreed to cooperate in defending the security and strategic interests of both countries. South Korea's deployment of army and marine units to South Vietnam in the 1960s and 1970s demonstrated its commitment to meeting its obligations under the treaty. By 1990 the United States had stationed 44,500 military personnel in South Korea--a signal to North Korea and other countries in the region that Washington would meet its security commitments to Seoul under the Mutual Defense Treaty.
Data as of June 1990